Thank you for your quick response and apologies for my delay in replying. That you haven't seen this problem before tells me that the glitch is rooted in either my particular laptop or in the peculiarities of the way I'm using the software rather than in not the software itself. Indeed, on reflection, I think this problem started when I installed on this computer.
As to the computer, I'm using Windows 11 fully updated running on an HP OMEN gaming laptop. This could be some weird interaction with the NVidia graphics. The graphics card has a 165Hz refresh rate and I note often that Maple does not fully refresh the screen. You might notice on the screenshot I originally sent that the leading part of the toolbar and the tabs for "pallet" and "workbook" are missing completely. The glitch is quite ephemeral, usually showing up only after Maple has been running for several hours and it clears completely when I close/restart Maple. It does not affect the files even if I save them after the odd characters appear.
I have been using the start up code as a platform to test out and dissect the various procedures in an old maple package. This way I can isolate a procedure, test it, and understand the algorithm behind it. Thus I'm doing a lot of copying from the editor to the worksheet, but I have not noticed any glitches appearing immediately when I copy text. Your suggestion about using the code window is something that I will try out.
If I can find a situation where I can reproduce the glitch I will send the work sheet, but so far it does not persist after restarting maple. Thanks for your attention.