If you double click or use "hollow" button on Media sources, playlist or context panel, it is undocked / detached from main window. According to http://userbase.kde.org/Amarok/Manual/ConfiguringAmarok/ChangingLayout#Undocking_Amarok_panes , hollow button should stay in the floating panel, but it is not, so there is no way to dock / attach it back. Double click does not work also. Reproducible: Always Steps to Reproduce: 1. Choose a panel in Amarok's main window. 2. Click the hollow button or double click it in panel title bar; the panel now floats free, detached / undocked from main window. Actual Results: Hollow button is missing in undocked panel. Expected Results: The floating panel should have a way to dock it back. Workaround: you could restart Amarok's layout by deleting "State" setting from [MainWindow] section in %APPDATA%\.kde\share\config\amarokrc
*** This bug has been marked as a duplicate of bug 300753 ***