OS X: main window doesn't become key.

When ordering a key window out Cocoa
tries to find a new KEY window. Looks like it prefers the current MAIN
window and since QNSPanel is never a main window, Cocoa is breaking
the stack order. To avoid this - try to change the key
window BEFORE ordering out a window.
The application has a stack of all open windows (visible and hidden),
we iterate through this stack starting from our current key window
and look for the nearest window below, that can become a new key window.
Most probably, it will be our transient parent :)
This code will change (potentially) the key window _only_
if there is a transient parent.

Task-number: QTBUG-39809
Change-Id: I96b630799341875fc7e38dabf1ff6416338e687b
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoawindow.mm b/src/plugins/platforms/cocoa/qcocoawindow.mm
index 4d0458a4aa..19d0f7a987 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.mm
+++ b/src/plugins/platforms/cocoa/qcocoawindow.mm
@@ -80,6 +80,32 @@ static bool isMouseEvent(NSEvent *ev)
     }
 }
 
+static void selectNextKeyWindow(NSWindow *currentKeyWindow)
+{
+    if (!currentKeyWindow)
+        return;
+
+    const QCocoaAutoReleasePool pool;
+
+    if ([[NSApplication sharedApplication] keyWindow] != currentKeyWindow)
+        return;//currentKeyWindow is not a key window actually.
+
+    NSArray *const windows = [[NSApplication sharedApplication] windows];
+    bool startLookup = false;
+    for (NSWindow *candidate in [windows reverseObjectEnumerator]) {
+        if (!startLookup) {
+            if (candidate == currentKeyWindow)
+                startLookup = true;
+        } else {
+            if ([candidate isVisible] && [candidate canBecomeKeyWindow]) {
+                [candidate makeKeyWindow];
+                break;
+            }
+        }
+    }
+}
+
+
 @interface NSWindow (CocoaWindowCategory)
 - (NSRect) legacyConvertRectFromScreen:(NSRect) rect;
 @end
@@ -588,6 +614,9 @@ void QCocoaWindow::hide(bool becauseOfAncestor)
     foreach (QCocoaWindow *childWindow, m_childWindows)
         childWindow->hide(true);
 
+    if (window()->transientParent() && m_nsWindow == [[NSApplication sharedApplication] keyWindow])
+        selectNextKeyWindow(m_nsWindow); // Otherwise, Cocoa can do it wrong.
+
     [m_nsWindow orderOut:nil];
 }