Method InsertStretchSpacer

Inserts stretchable space to the sizer.

ISizerItem InsertStretchSpacer(int index, int proportion = 1)

index int: Item index.
proportion int: Used in IBoxSizer and similar sizers to indicate if a child of a sizer can change its size in the main orientation of the sizer - where 0 stands for not changeable and a value of more than zero is interpreted relative to the value of other children of the same sizer. For example, you might have a horizontal sizer with three children, two of which are supposed to change their size with the sizer. Then the two stretchable windows would get a value of 1 each to make them grow and shrink equally with the sizer's horizontal dimension.

More readable way of calling: "Insert(0, 0, proportion)".