I use the scripting libraries heavily when developing in ignition. I also use the copy and paste function frequently because I develop my new scripts in the script console, and then typically copy it into a scripting library file that I have created.
I have noticed that when I open a scripting library file to check or verify some bit of script that I have created, at random script that I copied will paste into that open file... This has happened so many time that I know its not me triggering a paste in any way. It seems to be when I scroll down the page and reach the end, the clipboard contents are then pasted where ever my cursor landed (if I clicked the page).... Has anyone else experienced this, and has anyone found a solution? It drives me crazy, because (of course) it will cause my scripts in that library file to stop working... Then I have to back track and usually find that a new script was pasted into the middle of an old one !
This happens often enough that surely I am not the only one experiencing it .
Thanks in advance for any information anyone has on this...
I never noticed it before, but I tried this out and it seems the middle mouse button (pressing down your scroll wheel) is a shortcut for pasting from your clipboard.
I suspect this is what is triggering the paste when you are scrolling through a script. Not sure how you would go about disabling that shortcut (if you can).
Best I have is to try not to press down the scroll wheel when you are using it... 
I have this issue with certain logitech mouses on my windows 11 lenovo thinkpad. It would randomly pull up the right click/page up menu, and then I would accidentally select my whole text if I pressed A and then overwrite it. Very frustrating - but I never experienced this just from Ignition. I agree it's likely a mouse, specifically the wheel/third button press issue.
I'm sorry I didn't mean to delete this sir. I was trying to remove my reply ... everyone that posted nailed it... Middle mouse button.
I accidentally deleted your other reply... but you were correct - I don't know how to fix the issue yet... because I have no setting for the center wheel button press on this mouse... it just auto pastes. Thanks for your input...I really appreciate it. That puts me a little closer to fixing it anyway. I should have considered that ... lol, oh well.