FWIW -
In svn branch wxpropgrid_debugger, file plugins\debuggergdb\gdb_commands.h, "class GdbCmd_TooltipEvaluation", routine "void ParseOutput(const wxString& output)", toward the end of the routiine, I think there is a problem with the variable s_pWin.
It appears some code was added (relative to current trunk) to avoid invoking the tipwindow if the mouse has moved. As a result of that addition, it seems s_pWin can be left with a value of an item that was "Close()"ed in a previous iteration, such that subsequent attempts to "Close()" that old item could occur, which might be a bad thing.
Didn't see anywhere else where s_pWin was being cleared to avoid this potential problem, but I may be overlooking something - and I don't know for sure that the "Close()" will render the item invalid, but...
it looks suspicious to me.