Afraid it will not... at least not as it looks right now. When added to the panel, it produces really nasty drawing errors, and it has the same resizing problem as wxGrid. Worse yet, it shows in 16x16 unless you explicitely give a fixed size... If you specify the dialog as the property grid's parent (instead of a panel), it draws really fine, albeit over all other controls, and not in the correct place either...
Maybe you are not thought to manually add items to a XRC created dialog at all (although I cannot think of a reason not to), or maybe I just don't know how to do it properly... either way, it does not work as easily as one would expect. The compiler flags dialog is created from XRC too, so it will have the same problem.