SUMMARY
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If you open the wastebin on your desktop, Dolphin pops up. If you then click on the close button on the window, the window doesn't close the first time. You need to repeat the action two times. Sometimes I get also erratic strange behaviours with the Close Tab and Close Window keyboard shortcuts when I have more than one tab and the wastebin tab open in Dolphin. If I use Close Tab and then Close Window shortcuts, the wastebin tab is reopened.
***


STEPS TO REPRODUCE
A) DOUBLE CLOSE
1. Double click on the wastebin icon on the desktop;
2. Click on the close button on the window.

B) SHORTCUT QUIRKINESS
1. Open more than one tab in Dolphin;
2. Open the wastebin tab in the same Dophin window;
3. Use Close Tab Shortcut;
4. Use Close Window shortcut;

OBSERVED RESULT
A) The window doesn't close the first time. You need to repeat the action two times.
B) The wastebin tab is reopened.

EXPECTED RESULT
A) The window should be closed.
B) The wastebin tab should be closed/the window should be closed.

SOFTWARE/OS VERSIONS

Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 5.27.6
KDE Frameworks Version: 5.108.0
Qt Version: 5.15.10

ADDITIONAL INFORMATION