Windows: Clear window under mouse in destruction of platform window.

Task-number: QTBUG-32042

Change-Id: I8aa5df84b7ca6deb47e0c3eff9a6a7d2c4793553
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Doc: Add keywords for qmake variable/function reference pages

In the Help mode in Qt Creator, many have accustomed to search e.g.
for 'qmake variable reference' which no longer exists as a title in
the qmake documentation.

This change provides easier access to the qmake reference by
creating keywords for them, making them appear in search results
for searches starting with 'qmake'.

Task-number: QTBUG-32268
Change-Id: If60a0cdc11464a8aeb50c62ddbde9683326e1384
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
Fix handling of non-latin1 shortcuts

This patch enables non-latin1 shortcut handling on Qt5/X11.

Task-number: QTBUG-32274
Change-Id: Ia084258b956128ffade8eddfbcb18af334d79a59
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>