Modified reparenting to correctly deal with native child widgets

Both reparenting and modification of window flags are done by calling
QWidget::setParent.  If either the parent changes, or a non-top-level
widget becomes top-level (as a result of OR-ing Qt::Window into its
window flags), a new native window ID is created for the widget.  The
Symbian implementation of setParent_sys had a flaw which manifested
itself in the following situation:

1. We start with a native widget X, and its child Y, which is also
native.  There exist parent-child relationships between the associated
CCoeControl instances, and the native windows (represented by RWindow
handles).
2. X gets a new native window created as a result of a call to
setParent.
3. QWidgetPrivate::reparentChildren calls SetParent on Y's control, to
re-establish the parent-child relationship.

The problem is that the window owned by Y's control now has no parent,
so if we try to re-size the widget, the window server panics the client
thread (WSERV-52).

Because Symbian does not allow existing windows to be re-parented, and
nor does it allow a window-owning control to re-create a new window,
the only way to provide Y's window with a parent is to destroy the
control and create a new one, passing in X's new window to the
CCoeControl::CreateWindowL function.

The changes made are as follows:

a) QWidgetPrivate::reparentChildren is therefore modified to call
create_sys, with destroyOldWindow set to true.
b) QWidgetPrivate::create_sys is modified to take account of the value
of this flag in all cases.  (Previously it only did so if a new WId was
passed in by the caller).
c) The call to setWinId is delayed until the control and window are
fully initialized.  This is to allow us to emit a new event,
WinIdChanged, from setWinId, in order to inform the widget that its
winId has changed.
d) QWidgetPrivate::activateSymbianWindow is modified in order to
support this change of call ordering.

Note that QWidgetPrivate::create_sys requires some re-factoring in
order to remove the redundancy between the top-level and child widget
cases.

Task-number: QTBUG-4664
Reviewed-by: axis

0 files changed, 0 insertions, 0 deletions