A dark indigo CSS theme for Firefox and a large collection of privileged scripts to add new buttons, menus, behaviors and other opinionated features. The theme is similar to other userChrome stylesheets, but it's intended for use with an autoconfig loader like fx-autoconfig, since it uses JavaScript to implement its more functional features.
Hold down alt+shift and click the mouse button to drag as usual
Still holding the mouse button, but release the alt+shift. You can still drag around the window as expected.
Release the mouse button. At this point, since no alt+shift button is pressed, the mouse shouldn't be able to drag the window. But it still can do so. This makes it impossible to normally interact with the UI, like click on the urlbar to enter a new url.
To reproduce the buggy behavior: