Open + Save File window buggy in several applications (resizing left side also changes right side, moving window moves application, etc.)

I'm using Ubuntu 20.04, and several applications (Emacs, Firefox, Okular, Libre Office, OpenSCAD) all have buggy popup windows for opening and saving files. For example, when saving a file in Firefox using ctrl+s, the popup window where one specifies file name and location exhibits the following behaviour:

1. Adjusting the top edge of the window also moves the bottom edge and vice versa (dragging the top side up/down moves the bottom side down/up)
2. Adjusting the left edge of the window also moves the right edge and vice versa (dragging the left side left/right moves the right side right/left)
3. Moving the popup window also moves the application window (most annoyingly: it de-maximizes the application window if it was maximized)

Is this a problem with the applications or is this a problem with my system?

Solution 1:

This is not a problem with your system. This is how it works by default. Modal dialogs (e.g. a file dialog) are attached to their parent window and cannot be moved. The parent window is darkened. Parent window and the dialog are moved together. This gives a visual hint that you need to cope first with the dialog before being able to continue working.

Fortunately, this behaviour can be turned off with the following command

gsettings set org.gnome.mutter attach-modal-dialogs false

The setting is also exposed in Gnome Tweaks (not installed by default) on the Windows tab ("Attach Modal Dialogs").