collapse

collapse
Type: one of the values below
Determines which side of the splitter is collapsed when its grippy is clicked. If this attribute is not specified, the splitter will not cause a collapse. You should put a grippy element inside the splitter when it is used for collapsing.
none
No collapsing occurs.
before
When the grippy is clicked, the element immediately before the splitter in the same parent is collapsed so that its width or height is 0.
after
When the grippy is clicked, the element immediately after the splitter in the same parent is collapsed so that its width or height is 0.
both
Either the element immediately before the splitter, or the element immediately after the splitter can be collapsed, if the size of that element would fall below the minimum size due to the position of the splitter.