Ensure a small spanned column doesn't shrink its columns too much by checking for min column sizes

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75379 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
fix missing/incorrect GTK runtime version checks

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75381 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
just put GtkBorder variable on the stack
fixes missing runtime version check

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75382 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775