When dragging a button from the title bar in the Buttons tab of the Window Decorations KCM, an overlay shows above the pool of buttons with the text "Drag here to remove button" and an icon underneath That icon is not needed because it's clear that dragging an icon from the title bar to the pool of available icons will remove it from the title bar, and it is not aesthetically pleasing in this screen either. I'd therefore suggest to remove the icon.
Here's a patch: https://phabricator.kde.org/D20968
Git commit 48cacae8cfb4f2c1e82d191a19dc4515f1c897f3 by Nate Graham. Committed on 02/05/2019 at 23:07. Pushed by ngraham into branch 'master'. [kcmkwin/kwindecoration] Refine drag-and-drop button UI Summary: - Reduce the fake titlebar's height so it matches the real titlebar a bit better - Reduce background opacity while dropping button to diminish visual noise - Increase label size - Re-word label for greater clarity - Remove redundant icon (the text is enough) FIXED-IN: 5.16.0 Test Plan: {F6804068, size=full} Reviewers: #vdg, #kwin, GB_2, davidedmundson Reviewed By: #vdg, #kwin, GB_2, davidedmundson Subscribers: GB_2, abetts, kwin Tags: #kwin Differential Revision: https://phabricator.kde.org/D20968 M +8 -18 kcmkwin/kwindecoration/package/contents/ui/Buttons.qml https://commits.kde.org/kwin/48cacae8cfb4f2c1e82d191a19dc4515f1c897f3