Prematurely creating a dialog as a sheet causes problems

Prematurely creating a dialog as a sheet and then calling
exec() on it will show a window w/o decorations. The problem is
that first telling a window to be a sheet, and then tell it to
exec, is unambigious. Because doing the latter implies application
modality (when modality is not set), which again implies not
using a sheet. Calling exec (and setting modality) will win over
window flags, so in this case, we now recreate the window as a
normal app-modal dialog.

Task: 254524
Reviewed-by: Trenton Schulz

1 files changed, 4 insertions, 0 deletions

diff --git a/src/gui/kernel/qwidget.cpp b/src/gui/kernel/qwidget.cpp
index fb9084e..1e0f09c 100644
--- a/src/gui/kernel/qwidget.cpp
+++ b/src/gui/kernel/qwidget.cpp
@@ -9801,6 +9801,10 @@ void QWidget::setAttribute(Qt::WidgetAttribute attribute, bool on)
             data->window_modality = (w && w->testAttribute(Qt::WA_GroupLeader))
                                     ? Qt::WindowModal
                                     : Qt::ApplicationModal;
+            // Some window managers does not allow us to enter modal after the
+            // window is showing. Therefore, to be consistent, we cannot call
+            // QApplicationPrivate::enterModal(this) here. The window must be
+            // hidden before changing modality.
         }
         if (testAttribute(Qt::WA_WState_Created)) {
             // don't call setModal_sys() before create_sys()