Style.Rect_dimSourceall_px v creates a rectangle with all edges set to v pixels, using Length_percentage.length.
all_px_auto v creates a rectangle with all edges set to v pixels, for use with auto-capable properties like margin and inset.
xy_px ~x ~y creates a rectangle with horizontal edges set to x pixels and vertical edges set to y pixels.
xy_px_auto ~x ~y is the auto-capable variant of xy_px, suitable for margin and inset.
horizontal_px v creates a rectangle with left and right set to v pixels and top/bottom set to zero.
horizontal_px_auto v is the auto-capable variant of horizontal_px.
vertical_px v creates a rectangle with top and bottom set to v pixels and left/right set to zero.
vertical_px_auto v is the auto-capable variant of vertical_px.