Show "hint" wxTextCtrl attribute in the xrc sample.

Rearrange the contents of the wxTextCtrl page in two columns to make space for
the new control.

This should have been part of r76629 but was forgotten.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77001 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Add a more complete example of different controls variants in XRC.

Add a dialog showing all the existing variants of a few common controls to
allow seeing at a glance how do they look.

See #16247.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77002 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775