Intellij - what is this strange selection, and how do I turn it off?
Solution 1:
I think you have enabled 'column selection'.
Option can be toggled via these methods:
Menu Bar ->
Edit->Column selection mode
Document Body ->
Right Click->Column selection mode
Keyboard Shortcut ->
ALT + SHIFT + INSERT
Solution 2:
The column select mode is enabled, use Alt+Shift+Insert to enable or disable this mode.