Recompute the tooltip width when changing its text in wxMSW.

This avoids unnecessarily wrapping the tooltips if they are set to a longer
string than their initial value later.

Closes #4685.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75756 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Don't show windows with "hidden" XRC attribute at all.

This is better than showing them initially and then hiding them if only
because it avoids the unexpected wxEVT_SHOW events being generated.

Closes #15919.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75757 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775