computes the bounds of the scrollbar handle from the scrollbar size and the handles offset and size.
offset is in the range 0..1 and defines the position of the scroll handle
size is in the range 0..1 and defines the size of the scroll handle
See Implementation
computes the bounds of the scrollbar handle from the scrollbar size and the handles offset and size.
offset is in the range 0..1 and defines the position of the scroll handle
size is in the range 0..1 and defines the size of the scroll handle