Backported layout fixes portion of r75105


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75218 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Backported r75107: Fixed selection bug.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75219 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775