Add default ctor and Create() to wxContextHelpButton.

Allow two step creation of wxContextHelpButton.

Closes #14848.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75394 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Remove wx/generic/colrdlgg.h from common GUI headers.

This header is not used in all ports, notably not in wxMSW nor wxGTK.

See #15753.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75395 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Treat empty variants as null ones in wxMSW OLE code.

Simply ignoring VT_EMPTY variants doesn't make any sense and can result in
completely unexpected results, so don't do it.

Closes #15757.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75396 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Document wxMediaState enum.

Closes #15760.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75397 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Add wxHtmlWindow::SetDefaultHTMLCursor().

This allows to change the cursors used by any HTML windows, before creating
them.

Closes #15324.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75398 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775