This is my script jfiddle. I do not know the resolution of your screen. Please change a height of the grid so its frame has a vertical scroll bar. Then click on collapse, the scroll bar must disappear from the frame and you will see that grid width is not changed.
Thank you! Changing a height/width on collapse event triggers resize, but it does not affect the space specified on the second image. The width of grid is set to 100%. Actually the whole grid is properly resized. For some reason its internals – the last column and vertical scroll bar are misplaced. Please, help.