Fixed drawing glitch with vertical MSW toolbars.

Fixed drawing glitch with vertical MSW toolbars.

In case of a certain amount of whitespace at the bottom of a vertical toolbar it would not be drawn correctly: the more whitespace the more painting would be clipped starting from the left (covering the whole height of the toolbar) until the toolbar would look completely empty.

This was reproducible using the toolbar sample, setting the toolbar on the left or right edge of the window and then increasing the height of the window sufficiently.

Regression since r62971.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67074 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775