Don't let contentItem be FINAL in order to allow shadowing.

For subclasses that adds menubars, toolbars etc, the plan is to expose
another item (the item excluding the menubars, toolbars) as a
contentItem.

Task-number: QTBUG-32443

Change-Id: Id12fc50efde3fdf363e4528dd5de17177ddef24f
Reviewed-by: Alan Alpert (Personal) <416365416c@gmail.com>
Work around Nouveau driver bugs

Change-Id: I25311a2bd88f41087352e0a43ba505f4e27b7e85
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>
QtQuick.Dialogs: handle more keyboard shortcuts

The Back button on Android should close the dialog, but there is a bug
that Qt only receives the release, not the press.  Otherwise Esc should
do the same, Enter should accept, it should be possible to copy the
text from the MessageDialog, copy colors to and from the ColorDialog,
etc.

Change-Id: Ib4d4c58cde9f4bb00ce3d46e2f9ea1aad9d52bb0
Reviewed-by: Liang Qi <liang.qi@digia.com>
QtQuick.Dialogs: fake window decoration clips, is opaque for touch

This is the wrapper for dialogs on platforms that don't have top-level
windows.  Mouse events over any unused area in the dialog would fall
through to the surrounding mouse area and close the dialog.  Now they
don't.  Clipping is enabled to ensure that dialog contents don't
overflow the "window" frame.

Change-Id: Ia3c0ae44bb47d46981daac9febd4cc93228dd20f
Reviewed-by: Liang Qi <liang.qi@digia.com>
QtQuick.Dialogs MessageDialog: use Flow for button layout

On mobile platforms the dialog can have more buttons than horizontal
space to show them, so it's better to let them wrap around to ensure
they are all visible.  But Flow does not try to maximize its
implicitWidth, so we have to calculate it at the right time before
showing the dialog.

Change-Id: I5667aa90539f291ae040f2e125abc2dea968f9ac
Reviewed-by: Liang Qi <liang.qi@digia.com>
QtQuick.Dialogs DefaultFileDialog: visual improvements

Make spacing of controls consistent with the other dialogs.  It was
too conservative for high-resolution displays anyway.

Change-Id: I095d0c8f136b6692cc9c4ac01db748dbef205867
Reviewed-by: Liang Qi <liang.qi@digia.com>
QtQuick examples make use of the new pixelDensity property

Change-Id: I273fc08405724158fbf7c7d410bfa38fef4600b1
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>