Make disabling submenus work in wxMSW.

As submenu items don't have a valid ID, we need to address them by their
position when calling EnableMenuItem() -- and for simplicity do it for all the
items.

Closes #16747.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78324 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Fix flickering when resizing a frame with status bar in wxMSW.

The flicker was only visible under Windows XP or when using a class theme
and was due to mis-positioning the status bar initially in PositionStatusBar().
Fix this by adjusting its position by the toolbar offset before calling its
SetSize().

Closes #16705.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78325 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Revert "Add support for reading multi string values to wxRegKey."

Reverts r78136 (see #15727) because the multi-string values in Windows
registry are actually not "name=value" pairs at all but just NUL-separated
strings and the API provided for reading them was inappropriate.

Also see #16719.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78326 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Fix reading of not NUL-terminated strings using wxRegKey.

Even though this is typically the case, some strings in Windows registry are
not NUL-terminated, deal with them correctly by using the explicit length.

Closes #16719.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78327 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775