# Style Properties

The style properties associated with styles control how Displayables are shown. Style properties can be either given without a prefix, in which case they apply to all states of the displayable, or with a prefix that limits the property to a limited number of states.

## Style Property Prefixes

Applying a prefix to a style property indicates allows a displayable to change it's look in response to its focus or selection status. For example, a button can change its color when the mouse hovers above it, or to indicate when the choice represented by the button is the currently selected one.

There are five states a displayable can be it.

insensitive

  Used when the user cannot interact with the displayable.

idle

  Used when the displayable is neither focused nor selected.

hover

  Used when the displayable is focused, but not selected.

selected_idle

  Used when the displayable is not focused, and is selected.

selected_hover

  Used when the displayable is focused and selected.

Button and Bar displayables (and their variants) update their state, and the state of their children, in response to events. For example, when the user puts his mouse over an unselected button, it and all its children will be put into the hover state.

Style property prefixes allow one to set style properties for the different states. There is a system of implications set up, so that a prefix can imply setting the property for more than one state.

The implications are:

prefix | states implied by prefix
--- | ---
(no prefix) | insensitive, idle, hover, selected_idle, selected_hover
`idle_` | idle, selected_idle
`hover_` | hover, selected_hover
`selected_` | selected_idle, selected_hover
`insensitive_` | insensitive
`selected_idle_` | selected_idle
`selected_hover_` | selected_hover
`selected_insensitive_` | selected_insensitive

Using a text button, we can show this in action. Text buttons use two styles by default: `button` for the button itself, and `button_text` for the text inside the button. The `background` style property sets the background of a button, while the `color` property sets the color of text.:

    # The button background is gray when insensitive, light
    # blue when hovered, and dark blue otherwise.
    style button:
        background "#006"
        insensitive_background "#444"
        hover_background "#00a"

    # The button text is yellow when selected, and white
    # otherwise.
    style button_text:
        color "#fff"
        selected_color "#ff0"

## Style Property Values

Each style property expects a specific kind of data. Many of these are standard Python types, but a few are novel. Here are descriptions of the novel kinds of value a style property can expect.

position

  Positions are used to specify locations relative to the upper-left corner of the containing area. (For placement and size, the containing area is given by the layout the displayable is in, if one is given, or the screen otherwise. For anchors, the containing area is the size of the displayable itself.)

  The way a position value is interpreted depends on the type of the value:

  int (like 0, 1, 37, or 42)

    An integer is interpreted as the number of pixels from the left or top side of the containing area.

  float (like 0.0, 0.5, or 1.0)

    A floating-point number is interpreted as a fraction of the containing area. For example, 0.5 is a point halfway between the sides of the containing area, while 1.0 is on the right or bottom side.

  absolute(value, /)

    For example, `absolute(100.25)`, or `absolute(a+b)` when both `a` and `b` may be floats or ints.

    An `absolute` number is interpreted as the number of pixels from the left or top side of the screen, when using subpixel-precise rendering.

  position(absolute, relative, /)

    For example, `position(-10, .5)`.

    A combination of absolute, which will be treated as an absolute position, and relative, which will be treated as a relative position, both being as described above. The two components are added together to form the final position.

    Both parameters should always be passed, otherwise unspecified results may occur.

displayable

  Any displayable. If a displayable contains a "[prefix_]" substitution, a prefix search is performed as described below.

color

  Colors in Ren'Py can be expressed as strings beginning with the hash mark (#), followed by a hex triple or hex quadruple, with each of the three or four elements consisting of a one or two hexadecimal character color code.

  In a triple, the components represent red, green, and blue. In a quadruple, the components represent red, green, blue, and alpha. For example:

  - `"#f00"` and `"#ff0000"` represent an opaque red color.

  - `"#0f08"` and `"#00ff0080"` represent a semi-transparent green color.

  The color triples are the same as used in HTML.

  Colors can also be represented as a 4-component tuple, with the 4 components being integers between 0 and 255. The components correspond to red, green, blue, and alpha, in that order.

  - `(0, 0, 255, 255)` represents an opaque blue color.

  Finally, colors can be an instance of `Color`.

### Style Prefix Search

When a style property contains the "[prefix_]" substitution, a prefix search is performed. The prefix search is performed separately for each state, including states that are implied by the original property assigned.

For example, if we have:

    style button:
        hover_background "[prefix_]background.png"

separate searches are performed for the hover and selected_hover states. The prefixes searched vary based on the state.

state | search order
--- | ---
idle | "idle_", ""
hover | "hover_", "",
insensitive | "insensitive_", "", "idle_"
selected_idle | "selected_idle_", "idle_", "selected_", ""
selected_hover | "selected_hover_", "hover_", "selected_", ""
selected_insensitive | "selected_insensitive_", "hover_", "selected_", "", "selected_idle_", "idle_"

When a search is performed, each prefix is tried in the order given. The string has "[prefix_]" replaced with the prefix, and then Ren'Py checks to see if a loadable file or image with that name exists. If the file or image exists, the search stops and the displayable found is used. Otherwise, it proceeds to the next prefix.

The style prefix is passed through displayables that do not take user input, including containers, transforms, and frames.

As an example of how this can be used, if the files `idle_button.png` and `hover_button.png` exist (and no other files ending in `button.png` do):

    style button:
        background "[prefix_]button.png"

is equivalent to:

    style button:
        idle_background "idle_button.png"
        hover_background "hover_button.png"
        insensitive_background "idle_button.png"

        selected_idle_background "idle_button.png"
        selected_hover_background "hover_button.png"
        selected_insensitive_background "idle_button.png"

## List of All Style Properties

The style properties control the look of the various displayables. Not all style properties apply to all displayables, so we've divided them up into groups.

### Position Style Properties

These properties apply to all displayables, and mostly control the position of a displayable inside the area allocated to it by a layout, or on the screen when not inside a layout.

alt - string or None

  Alternative text used for the displayable when self-voicing is enabled. See the self voicing section for more information.

xpos - position

  The position of the displayable relative to the left side of the containing area.

ypos - position

  The position of the displayable relative to the top side of the containing area.

pos - tuple of (position, position)

  Equivalent to setting xpos to the first component of the tuple, and ypos to the second component of the tuple.

xanchor - position

  The position of the anchor relative to the left side of the displayable.

yanchor - position

  The position of the anchor relative to the top side of the displayable.

  If the displayable is a `Text()`, then there is one special value of this property. If the property is set to renpy.BASELINE, the anchor is set to the baseline of the first line of text.

anchor - tuple of (position, position)

  Equivalent to setting xanchor to the first component of the tuple, and yanchor to the second component of the tuple.

xalign - float

  Equivalent to setting xpos and xanchor to the same value. This has the effect of placing the displayable at a relative location on the screen, with 0.0 being the left side, 0.5 the center, and 1.0 being the right side.

yalign - float

  Equivalent to setting ypos and yanchor to the same value. This has the effect of placing the displayable at a relative location on the screen, with 0.0 being the top, 0.5 the center, and 1.0 the bottom.

align - tuple of (float, float)

  Equivalent to setting xalign to the first component of the tuple, and yalign to the second.

xcenter - position

  Equivalent to setting xpos to the value of this property, and xanchor to 0.5.

ycenter - position

  Equivalent to setting ypos to the value of this property, and yanchor to 0.5.

xycenter - tuple of (position, position)

  Equivalent to setting xcenter to the first component of the tuple, and ycenter to the second.

xoffset - int

  Gives a number of pixels that are added to the horizontal position computed using xpos and xalign.

yoffset - int

  Gives a number of pixels that are added to the vertical position computed using ypos and yalign.

offset - tuple of (int, int)

  Equivalent to setting xoffset to the first component of the tuple, and yoffset to the second component of the tuple.

xmaximum - int

  Specifies the maximum horizontal size of the displayable, in pixels.

ymaximum - int

  Specifies the maximum vertical size of the displayable in pixels.

maximum - tuple of (int, int)

  Equivalent to setting xmaximum to the first component of the tuple, and ymaximum to the second.

xminimum - int

  Sets the minimum width of the displayable, in pixels. Only works with displayables that can vary their size.

yminimum - int

  Sets the minimum height of the displayables, in pixels. Only works with displayables that can vary their size.

minimum - tuple of (int, int)

  Equivalent to setting xminimum to the first component of the tuple, and yminimum to the second.

xsize - int or float

  Equivalent to setting xminimum and xmaximum to the same value. This has the effect of setting the width of the displayable. f the size is a float, it's relative to the width of the containing area.

ysize - int or float

  Equivalent to setting yminimum and ymaximum to the same value. This has the effect of setting the height of the displayable. If the size is a float, it's relative to the height of the containing area.

xysize - tuple of (int or float, int or float)

  Equivalent to setting xsize to the first component of the tuple, and ysize to the second component.

xfill - boolean

  If true, the displayable will expand to fill all available horizontal space. If not true, it will only be large enough to contain its children.

  This only works for displayables that can change size.

yfill - boolean

  If true, the displayable will expand to fill all available vertical space. If not true, it will only be large enough to contain its children.

  This only works for displayables that can change size.

area - tuple of (int, int, int, int)

  The tuple is interpreted as (xpos, ypos, width, height). Attempts to position the displayable such that it's upper-left corner is at xpos and ypos, and its size is width and height.

  It does this by setting the xpos, ypos, xanchor, yanchor, xmaximum, ymaximum, xminimum, yminimum, xfill, and yfill properties to appropriate values.

  This will not work with all displayables and all layouts.

mipmap - boolean or None

  This controls if textures created by this displayable are mipmapped. This applies only to certain displayables, including `Text()`, `Movie()`, and dissolves.

  If None, the default for this is taken from config variables such as `config.mipmap_text`, `config.mipmap_movies`, and `config.mipmap_dissolves`.

### Text Style Properties

antialias - boolean

  If True, the default, TrueType font text will be rendered anti-aliased.

adjust_spacing - boolean or str

  If True, Ren'Py will adjust the spacing of drawable-resolution text to match the spacing of the text rendered at virtual resolution, to ensure the size of frames and other containers holding text does not change.

  When set to False, text will not change in size, but it is the creator's responsibility to ensure there is enough space to layout text at any window size.

  When set to the string "horizontal", text will adjust in the horizontal direction only. When set to the string "vertical", text will adjust in the vertical direction only.

  Defaults to True for most text, but False for text in an `input`.

altruby_style - style or None

  If not None, this should be a style object. The style that's used for alternate ruby text.

axis - dict or None

  This allows the axes of a variable font to be set. If not None, this should be a dictionary mapping axis names to values. For example:

      style default:
          font "VariableFont.ttf"
          axis { "weight" : 500, "width" : 95 }

black_color - color

  When rendering an image-based font, black will be mapped to this color. This has no effect for TrueType fonts.

  This may be None in the case of ruby/furigana text, to use the same color as the parent text.

bold - boolean

  If True, render the font in a bold style. For a TrueType font, this usually involves synthetically increasing the font weight. It can also cause the font to be remapped, using `config.font_replacement_map`.

caret - displayable or None

  If not None, this should be a displayable. The input widget will use this as the caret at the end of the text. If None, a 1 pixel wide blinking line is used as the caret.

color - color

  The color the text is rendered in. When using a TrueType font, the font is rendered in this color. When using an image-based font, white is mapped to this color.

  This may be None in the case of ruby/furigana text, to use the same color as the parent text.

emoji_font - string

  The font that's used to render Emoji characters. This is automatically used when a sequence of one or more Emoji are encountered, and no font text tag is in use.

first_indent - int

  The amount that the first line of text in a paragraph is indented by, in pixels.

font - string

  A string giving the name of the font used to render text.

  For a TrueType font file, this is usually the name of the file containing the font (like `"DejaVuSans.ttf"`). To select a second font in a collection, this can be prefixed with a number and at sign (like `"0@font.ttc"` or `"1@font.ttc"`). For an image-based font, this should be the name used to register the font.

hinting - str

  Controls how the font will be hinted. This should be one of the following strings:

  "auto"

    The default, forces use of the Freetype auto hinter.

  "auto-light"

    Forces the use of the freetype auto hinter in light mode, which only hints vertically.

  "bytecode"

    Uses bytecode hinting information found in the font.

  "none"

    Does not hint the font.

  This may also be True, in which case the value is looked up in `config.font_hinting`.

hyperlink_functions - tuple of (function, function, function)

  This is a tuple of three functions relating to hyperlinks in text.

  The first item is the hyperlink style function. When called with a single argument, the argument of the hyperlink, it must return a style object to use for the hyperlink, such as `style.hyperlink_text`. Note that a style object is not a string.

  The second item is the hyperlink clicked function. This function is called when a hyperlink is chosen by the user. If it returns a value other than None, the interaction returns that value.

  The third item is the hyperlink focus function. This function is called with the argument of the hyperlink when the hyperlink gains focus, and with None when it loses focus. If it returns a value other than None, the interaction returns that value.

instance - string or None

  When using a variable font, this can be a string giving a named instance of the font to use. For example, if the font has a "Bold" instance, this can be set to "Bold" to use that instance.

italic - boolean

  If true, the text will be rendered in italics. For a TrueType font, this usually involves synthetically increasing the font slant. It can also cause the font to be remapped, using `config.font_replacement_map`.

justify - boolean

  If True, additional whitespace is inserted between words so that the left and right margins of each line are even. This is not performed on the last line of a paragraph.

kerning - float

  A kerning adjustment, the number of pixels of space that's added between each pair of characters. (This can be negative to remove space between characters.)

language - string

  Controls the language family used to break text into lines, and for certain other text transformations. Legal values are:

  `"unicode"` (default)

    Uses the Unicode linebreaking algorithm, which is suitable for most languages.

  `"japanese-strict"`

    Formats Japanese text in a "strict" manner. It forbids breaks before small kana and prolonged sound marks.

  `"japanese-normal"`

    Formats Japanese text in a "normal" manner. It allows breaks before small kana, prolonged sound marks, and certain hyphens.

  `"japanese-loose"`

    Formats Japanese text in a "loose" manner. It allows breaks before small kana , prolonged sound marks, iteration marks, inseparable characters, centered punctuation marks, and postfixes; and allows breaks before prefixes.

  `"korean-with-spaces"`

    Used for Korean text delimited by whitespace. This prevents linebreaking between adjacent Korean characters.

  `"thaic90"`

    Used for Thai text displayed in fonts that support the C90 encoding for Thai. This combines groups of characters into single glyphs, allowing for better display of vowel and tone marks. Line breaking uses the unicode algorithm.

  `"western"`

    Allows breaking only at whitespace. Suitable for most languages.

  `"anywhere"`

    Allows breaking at anywhere without ruby.

  The three Japanese breaking modes are taken from the CSS3 text module.

layout - string

  Controls how words are allocated to lines. Legal values are:

  `"tex"` (default)

    Uses the Knuth-Plass linebreaking algorithm, which attempts to minimize the difference in line lengths of all but the last line.

  `"subtitle"`

    Uses the Knuth-Plass linebreaking algorithm, but attempts to even out the lengths of all lines.

  `"greedy"`

    A word is placed on the first line that has room for it.

  `"nobreak"`

    Do not line-break.

line_leading - int

  The number of pixels of spacing to include above each line.

line_overlap_split - int

  When in slow text mode, and two lines overlap, this many pixels of the overlap are allocated to the top line. Increase this if the bottoms of characters on the top line are clipped.

line_spacing - int

  The number of pixels of spacing to include below each line.

min_width - int

  Sets the minimum width of each line of that. If a line is shorter than this, it is padded to this length, with `textalign` used to specify where such padding is placed.

newline_indent - boolean

  If true, the `first_indent` indentation is used after each newline in a string. Otherwise, the `rest_indent` indentation is used.

outlines - list of tuple of (int, color, int, int)

  This is a list of outlines that are drawn behind the text. Each tuple specifies an outline, and outlines are drawn from back to front.

  The list contains (size, color, xoffset, yoffset) tuples. size is the amount the font is expanded by, in pixels. color is the color of the outline. xoffset and yoffset are the amount the outline is shifted by, in pixels.

  The outline functionality can also be used to give drop-shadows to fonts, by specifying a size of 0 and non-zero offsets.

  By default, size, xoffset and yoffset are scaled with the text. When given as the absolute type, they are not scaled. For example:

      style default:
          outlines [ (absolute(1), "#000", absolute(0), absolute(0)) ]

  will always produce a 1 pixel-wide border.

  Outlines only work with TrueType fonts. Outlines only work when applied to an entire Text displayable. They do not work when applied to a hyperlink, text tag, or other method that applies to only a portion of the text.

outline_scaling - string

  This determines how outline sizes and offsets are scaled when the window is scaled.

  `"linear"`

    The default, best for text with thick outlines. The window scaling factor is applied to the outline size, and then rounded to an integer. This looks better for thick outlines, but concentric outlines of similar thickness may become indistinguishable.

    The resulting width is always at least 1 pixel.

  `"step"`

    Best for text that uses thin outlines and text that uses multiple outlines. The window scaling factor is rounded down to an integer and applied to the outline size and offsets. This ensures that multiple outlines all scale together, without risk of eclipsing one another, but this yields different visual results depending on the size of the game window.

    The window scaling factor is always above 1.

prefer_emoji - boolean

  Some unicode characters have both Emoji and non-Emjoji presentations. This style property chooses if such characters are given the Emoji presentation or not.

rest_indent - int

  Specifies the number of pixels the second and later lines in a paragraph are indented by.

ruby_line_leading - int

  The number of pixels of spacing to include above each line that contains ruby text. This is in addition to `line_leading`.

ruby_style - style or None

  If not None, this should be a style object. The style that's used for ruby text.

shaper - "harfbuzz" or "freetype".

  The shaper used on text. This should be one of "harfbuzz" or "freetype". The harfbuzz shaper is more capable but only works on Ren'Py 8, while "freetype" works in Ren'Py 7 as well.

  The shaper takes a series of characters and turns it into a series of positioned glyphs. This is used for things like ligatures, Indic/Bhramic languages, and combining emjoi.

size - int

  The size of the font on the screen. While this is nominally in pixels, font files may have creative interpretations of this value.

slow_abortable - boolean

  If True, a click that reaches the Text object will cause the slow text to abort, which means that the rest of the slow text will be displayed instantly.

slow_cps - int or True

  If a number, shows text at the rate of that many characters per second. If True, shows text at the speed taken from the "Text Speed" preference.

slow_cps_multiplier - float

  The speed of the text is multiplied by this number. This can be used to have a character that speaks at a faster-than-normal rate of speed.

strikethrough - boolean

  If True, a line is drawn through the text.

textalign - float

  This is used when a line is shorter than the width of the text displayable. It determines how much of the extra space is placed on the left side of the text. (And hence, the text alignment.)

  0.0 will yield left-aligned text, 0.5 centered text, and 1.0 right-aligned text.

underline - boolean

  If True, an underline will be added to the text.

vertical - boolean

  If True, the text will be rendered vertically.

  There are multiple caveats:

  - If `shaper` is "freetype", vertical layout will likely be incorrect.

  - Harfbuzz will convert horizontal forms to vertical forms if those forms are present in the font.

  - Characters will be laid out top to bottom, right to left, but will not be rotated. This means that horizontal characters will be laid out one on top of another.

  - If vertical text information is not present in the font, it will be synthesized, but may be incorrect. Generally, ideographic text works better than non-ideographic text.

### Window Style Properties

Window properties are used to specify the look of windows, frames, and buttons. Margin Style Properties also form part of this group.

background - displayable or None

  A displayable that is used as the background of the window. This is often a `Frame()`, allowing the size of the background to scale with the size of the window.

  If None, no background is drawn, but other properties function as if the background was present.

foreground - displayable or None

  If not None, this displayable is drawn above the contents of the window.

left_padding - int

  The amount of space between the background and the left side of the window content, in pixels.

right_padding - int

  The amount of space between the background and the right side of the window content, in pixels.

xpadding - int

  Equivalent to setting left_padding and right_padding to the same value.

top_padding - int

  The amount of space between the background and the top side of the window content, in pixels.

bottom_padding - int

  The amount of space between the background and the bottom side of the window content, in pixels.

ypadding - int

  Equivalent to setting top_padding and bottom_padding to the same value.

padding - tuple

  When given a two-item tuple, equivalent to setting xpadding and ypadding to the two items. When given a four-item tuple, equivalent to setting left_padding, top_padding, right_padding, and bottom_padding to the four items.

size_group - string or None

  If not None, this should be a string. Ren'Py will render all windows with the same size_group value at the same size.

modal - boolean or callable

  If True, the window is treated as modal. Events will stop propagating through layers while the mouse is within the window or button. If False, the window is not modal.

  This may also be a callable function. If it is, the function is called with (ev, x, y, w, h), where ev is either a pygame event, or None to represent a generic mouse event; x and y are coordinates relative to the window, and w and h are the height and width of the window. If the callable returns true, the windows is treated as modal. If it returns false, it is not.

### Button Style Properties

child - displayable or None

  If not None, this gives a displayable that replaces the child of the button. For example, this (as insensitive_child) can be used to replace the contents of an insensitive button with an image that indicates the button is locked.

hover_sound - string

  A sound that is played when the button gains focus.

activate_sound - string

  A sound that is played when the button is activated (clicked). This is also played when a bar or drag is activated.

mouse - string

  The mouse style that is used when the button is focused. This should be one of the styles in `config.mouse`.

focus_mask - multiple

  A mask that's used to control what portions of the button can be focused, and hence clicked on. The type of this property determines how it is interpreted.

  Displayable

    The areas of the displayable that are not transparent cause the button to be focused.

  True

    The button itself is used as the displayable (so non-transparent areas of the button cause the button to be focused).

  callable

    If a non-displayable callable (like a function, method, or object with a `__call__` method) is given, the function is called with two arguments, the x and y offset from the top-left corner of the displayable.

    If the function returns a callable when called with two arguments, that callable is called with four arguments - the x and y offsets, and the width and height of the displayable.

    If the function returns true, the displayable is focused.

  None

    If none is given, the entire button can be focused.

keyboard_focus - boolean

  If True, the default, this button can be focused using the keyboard focus mechanism, if it can be focused at all. If False, the keyboard focus mechanism will skip this button. (The keyboard focus mechanism is used by keyboards and keyboard-like devices, such as gamepads.)

keyboard_focus_insets - (int, int, int, int) or None

  If not None, this should be a tuple of four integers, giving the number of pixels that are used to shrink the left, top, right, and bottom sides of the focus rectangle, when it's used for keyboard focus.

  This can be useful when buttons overlap. The keyboard focus algorithm doesn't work with overlapping buttons, and so this can be used to to shrink the size of the buttons internally, allowing focus to work.

key_events - boolean

  If True, keyboard-generated events are passed to the children of this button. If False, those events are not propagated. In this default style, this is set to True while the button is hovered, and False otherwise.

  Setting this to True can be used to propagate keyboard events to an input inside a button, even when the button isn't focused.

### Bar Style Properties

Bars are drawn with gutters on the left and right, that when clicked can cause the bar to move by a small amount. The remaining space is the portion of the bar that can change, with the amount on each side proportional to the bar's value as a fraction of the range.

The thumb is an area in the center of the bar that can be dragged by the user.

When a bar is drawn, the thumb's shadow is drawn first. Then the left/bottom and right/top sides of the bar, followed by the thumb itself.

Note that the valid sides of a bar depend on the value of the bar_vertical property. If it's True, the top and bottom sides are relevant. Otherwise, the left and right sides are used.

bar_vertical - boolean

  If True, the bar has a vertical orientation. If False, it has a horizontal orientation.

bar_invert - boolean

  If True, the value of the bar is represented on the right/top side of the bar, rather than the left/bottom side.

bar_resizing - boolean

  If True, we resize the sides of the bar. If False, we render the sides of the bar at full size, and then crop them.

left_gutter - int

  The size of the gutter on the left side of the bar, in pixels.

right_gutter - int

  The size of the gutter on the right side of the bar, in pixels.

top_gutter - int

  The size of the gutter on the top side of the bar, in pixels.

bottom_gutter - int

  The size of the gutter on the bottom side of the bar, in pixels.

left_bar - displayable

  The displayable used for the left side of the bar.

right_bar - displayable

  The displayable used for the right side of the bar.

top_bar - displayable

  The displayable used for the top side of the bar.

bottom_bar - displayable

  The displayable uses for the bottom side of the bar.

base_bar - displayable

  A single displayable that is used for left_bar/right_bar or top_bar/bottom_bar, as appropriate. (This can be used with thumb to make a slider or scrollbar.)

thumb - displayable or None

  If not None, this is a displayable that is drawn over the break between the sides of the bar.

thumb_shadow - displayable or None

  If not None, this is a displayable that is drawn over the break between the sides of the bar.

thumb_offset - int

  The amount that by which the thumb overlaps the bars, in pixels. To have the left and right bars continue unbroken, set this to half the width of the thumb in pixels.

mouse - string

  The mouse style that is used when the button is focused. This should be one of the styles in `config.mouse`.

unscrollable - string or None

  Controls what happens if the bar is unscrollable (if the range is set to 0, as is the case with a viewport containing a displayable smaller than itself). There are three possible values:

  `None`

    Renders the bar normally.

  `"insensitive"`

    Renders the bar in the insensitive state. This allows the bar to change its style to reflect its lack of usefulness.

  `"hide"`

    Prevents the bar from rendering at all. Space will be allocated for the bar, but nothing will be drawn in that space.

keyboard_focus - boolean

  If True, the default, this button can be focused using the keyboard focus mechanism, if it can be focused at all. If False, the keyboard focus mechanism will skip this button. (The keyboard focus mechanism is used by keyboards and keyboard-like devices, such as joypads.)

### Box Style Properties

These are used for the horizontal and vertical box layouts.

spacing - int

  The spacing between members of this box, in pixels.

first_spacing - int

  If not None, the spacing between the first and second members of this box, in pixels. This overrides the spacing property.

box_reverse - boolean

  If True, the placement of the items in the box will be reversed. When this is True, a hbox will be filled right-to-left, and a vbox will be filled bottom-to-top. This defaults to False.

box_wrap - boolean

  If True, then boxes will wrap when they reach the end of a line or column. If False (the default), they will extend past the end of the line.

box_wrap_spacing - int

  When box_wrap is True, this is the spacing between wrapped lines or columns. (So it is the vertical spacing between lines in a wrapped hbox, and the horizontal spacing between columns in a wrapped vbox.)

box_align - float or None

  This determines the alignment of rows or columns in a box. If 0.0, the default, rows are left-aligned and columns are top-aligned. If 0.5, it will center wrapped rows.

  When this is not None, addional space will not be offered to the child when `xfill` or `yfill` is set, ignoring the child's position in the box's primary direction.

order_reverse - boolean

  If False, the default, the items in the box will be drawn first-to-last, with the first item in the box being below the second, and so on. If True, this order will be reversed, and the first item in the box will be above all other items in the box.

box_justify - boolean or "first" or "all"

  If not False, the contents of the box will be justified - that is, the items inside the box will have the spacing between them adjusted so they evenly span the size of the box. True will cause all lines but the final line to be justified. "first" will cause only the first line to be justified. "all" will cause all lines to be justified, including the final line. Justified lines do not obey box_align, except when there is only one item in a line.

  When this is not false, addional space will not be offered to the child when `xfill` or `yfill` is set, ignoring the child's position in the box's primary direction.

### Grid Style Properties

These are the properties used by the grid and vpgrid displayables. Margin Style Properties also form part of this group.

spacing - int

  The spacing between cells of the grid, in pixels.

xspacing - int or None

  The spacing between cells of the grid in the horizontal direction, in pixels. This takes precedence over the spacing property when it is not None.

yspacing - int or None

  The spacing between cells of the grid in the vertical direction, in pixels. This takes precedence over the spacing property when it is not None.

### Fixed Style Properties

These are used with the fixed layout.

fit_first - boolean or "width" or "height"

  If True, then the size of the fixed layout is shrunk to be equal with the size of the first item in the layout. If "width", only the width is changed (the fixed will fill the screen vertically). Similarly, "height" only changes the height.

  The position of the child is ignored for the purpose of fit_first.

xfit - boolean

  If True, the size of the fixed layout is shrunk horizontally to match the right side of the rightmost child of the fixed.

yfit - boolean

  If True, the size of the fixed layout is shrunk vertically to match the bottom side of the bottommost child of the fixed.

When these properties are supplied, the children of the fixed are first offered the full area given to the fixed by its parent. Once the size and placement of the children are known, these properties are then used to select the size of the fixed.

### Margin Style Properties

Margin properties are used to add transparent space around some displayables. Most notably: windows, frames, buttons and outside a grid or vpgrid.

left_margin - int

  The amount of transparent space to the left of the displayable, in pixels.

right_margin - int

  The amount of transparent space to the right of the displayable, in pixels.

xmargin - int

  Equivalent to setting left_margin and right_margin to the same value.

top_margin - int

  The amount of transparent space above the displayable, in pixels.

bottom_margin - int

  The amount of transparent space below the displayable, in pixels.

ymargin - int

  Equivalent to setting top_margin and bottom_margin to the same value.

margin - tuple

  When given a two-item tuple, equivalent to setting xmargin and ymargin to the two items. When given a four-item tuple, equivalent to setting left_margin, top_margin, right_margin, and bottom_margin to the four items.