r/kde - [PLASMA TIP] You can resize the window in any direction by holding ALT + right mouse button and moving mouse in the direction you want to resize the widow
KDE is an international technology team creating user-friendly free and open source software for desktop and portable computing. KDE's software runs on GNU/Linux, BSD and other operating systems, including Windows.
https://www.reddit.com/r/kde/comments/6963sa/plasma_tip_you_can_resize_the_window_in_any/