These functions return the number of columns or rows being currently used and
not 0, unlike the existing Get{Cols,Rows}(), if the corresponding number is
determined dynamically.
Closes #10254.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@61750 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775