activateWindow() doesn't work

Hello!
I have two windows - the main one and the secondary window (an image viewer). Here is a code demostrating how I show the image viewer window:

Code:

---

if (! img_viewer->window.isVisible()) //if the viewer is not visible
   {
     img_viewer->window.show();
     activateWindow(); //trying to set focus back to the main window
     }
img_viewer->set_image (full_path); //just show an image
//at the QLabel

---

So the focus works in the following way:
1. When the image viewer window became visible (after the show() method), the focus moves to this image viewer window.
2. But I want to get the focus back into the main window. So I call activateWindow().
3. Nothing happens. The focus stays on the image viewer window.

What if you also call QWidget::setFocus() on a widget in your main window?

try to do like this

Code:

---

...
raise();
activateWindow();
...

---

Yes, I've tried raise(), and setFocus for the widget, etc - nothing changed, focus stays on the secondary window until I click on the main window.
Now I have found a bad solution:

Code:

---

img_viewer->window.show();
hide();
show();

---

After that, the focus moves to the main window. But I want to move the focus without any window disappearing :)

Are you testing this on Linux? I've seen cases were raise() did not have any effect. Does it help if you turn "desktop effects" off?

Yes, I'm on Linux, Qt 4.4.3. Desktop effect are turned off. Soon I'll test this focusing problem on Windows XP.

Update.
When I'm calling hide() and show() for the main window (after the image viewer window becomes active), I get those errors at console output:

X Error: BadWindow (invalid Window parameter) 3
Major opcode: 20 (X_GetProperty)
Resource id: 0x16055ff
X Error: BadWindow (invalid Window parameter) 3
Major opcode: 15 (X_QueryTree)
Resource id: 0x16055ff
X Error: BadWindow (invalid Window parameter) 3
Major opcode: 40 (X_TranslateCoords)
Resource id: 0x16055ff

So the problem is in the X-system?

Could you make a minimal compilable example-program demonstrating the problem and post it here?

I'll post an example a bit later. Currently I've solved the problem calling setWindowFlags (Qt::Tool) for the secondary window.