In KDE's Konsole, if I have a Konsole window open with multiple tabs and accidentally click and drag a tab off into its own window, is there any way to re-attach it to the tabs of the original Konsole window? I've tried dragging it back onto the window and holding down different keys, but I can't figure out a way to do it. Thanks.
I can not tell if and when this changed, but with Konsole 20.08.1 (I could test it on Arch Linux), detached tabs can be re-attached to their original window by:
Dragging them by their label in the tab bar.
To see the tab bar in windows containing one tab only, you may need to set:
"Configure Konsole" > "Tab Bar / Splitters" > "Appearance" > "Show: Always"
Dropping them anywhere on the target window, except for its title bar.
This will also work for newly created windows (i.e. for tabs that had not been previously detached) if "Configure Konsole" > "General" > "Run all Konsole windows in a single process" is checked (except for windows opened before this settings was applied).