This function sets up hints about how a window can be resized by the user. You can set a minimum and maximum size; allowed resize increments (e.g. for xterm, you can only resize by the size of a character); aspect ratios; and more. See the GdkGeometry struct.
widget the geometry hints used to be applied to or NULL. Since 3.20 this argument is ignored and GTK behaves as if NULL was set.
struct containing geometry information or NULL
mask indicating which struct fields should be paid attention to