Align
Controls how a widget deals with extra space in a single dimension.
Alignment only matters if the widget receives a “too large” allocation, for example if you packed the widget with the property@Gtk.Widget:hexpand property inside a class@Box, then the widget might get extra space. If you have for example a 16x16 icon inside a 32x32 space, the icon could be scaled and stretched, it could be centered, or it could be positioned to one side of the space.
Note that in horizontal context %GTK_ALIGN_START and %GTK_ALIGN_END are interpreted relative to text direction.
%GTK_ALIGN_BASELINE support is optional for containers and widgets, and it is only supported for vertical alignment. When it's not supported by a child or a container it is treated as %GTK_ALIGN_FILL.