I checked in the settings the option "Minimize to the system tray". At the first start, the main window is open. When I click on the minimize button, the window go normally in the system tray. Then, I click twice on the system tray icon, the window is restored. At this time, if I click the minimize button, the window is reduced in the right bottom of the screen (Radegast icon is always available in the system tray). If I try to restore the window from the contextual window menu, the window appears normally, but minimize and restore buttons are missing.
1. Start the program with the "Minimize to the system tray" option enabled (the window appears).
2. Minimize the main window with the minimize button (the window go in the system tray).
3. Restore the window (double click on the Radegast icon or select Restore from the contextual menu).
4. Minimize again the window (the window appears reduced on the desk).
5. Restore the window from the window contextual menu (minimize and restore buttons are now missing).