The system I’m working on is Wayland/GNOME/Mutter. My aim is to intercept all clipboard operations through a single point, to which I have decided modifying Mutter would be the best option (to my knowledge, a GNOME extension can’t help with intercepting pastes/D&D, and Mutter doesn’t support wl-roots which may or may not make a Wayland client a viable option otherwise). I’ve extensively researched code for other clipboard managers, Mutter, applications like LibreOffice/gedit, and GNOME extensions over the past several months in hopes of finding an answer to my solution, but to no avail.
Although not all has been failure. I have been able to intercept copy, drag, and drop operations, as well as some pastes, but only when they occur inter-application (as in data is copied from one application and pasted to another). From my understanding, many applications will store their own internal clipboard such that when the application recognizes it already owns the clipboard data, it doesn’t need to communicate with Mutter to retrieve said clipboard, therefore never triggering any functions for me to intercept. Would it be possible for me to somehow access the clipboard of the application that last copied data so that I can trick it into thinking it doesn’t own the data and has to request it from Mutter? Would this be possible in modifying Mutter source code or even through creating my own Wayland client?
My ultimate goal is to send a popup notification on copy/paste/d&d depending on the clipboard data. This must be done in a Mutter environment. I have spent an abundance of time researching and examining source code/other applications and building/testing my own patched versions of Mutter. Do you have any idea what other avenues I could take? If it’s impossible to complete this task all within the central point of a patched Mutter, what is the next best route or option?