Notify user less intrusively about overflow when previewing HTML printouts.

Notify user less intrusively about overflow when previewing HTML printouts.

We used to show a modal dialog if the page didn't fit horizontally but this
was too intrusive when the user was just previewing the output and not really
printing it. Moreover, the question of the message box ("Print" or "Cancel")
simply didn't make sense in this case.

Fix both problems by not showing this dialog at all when previewing. Instead,
notify the user with a much less intrusive info bar in the preview window.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64214 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775