From Nina Kalinina’s excellent revival of a forgotten 1983 GUI, a discovery of a hilarious accessibility bug:

VisiOn loves to beep at the user. It beeps every time a menu option is chosen or an on-screen button is clicked.

If you are tired of the noise, you’d appreciate that Application Manager has an option to replace the sound with a “visual beep”. It is implemented as a flashing area of 32x16 pixels around the mouse cursor. Every time the flashing is about to happen, an image “below” the cursor is preserved in RAM to be restored after the “visual beep” is over. However, the memory allocated for this bitmap is never freed. It takes between 200 and 1000 clicks to fill the RAM with useless copies of the mouse cursor, and then the system crashes.

If you have never heard of VisiOn, The Digital Antiquarian has a fun walkthrough that also happens to be the first chapter of an excellent series about the history of graphical user interfaces.