FWIW I can redo this with 6.6.18177.16151.
To reproduce I
- create a torus
- create several materials in the material editor
- ensure material editor is the panel that is open
- select the torus
M - several times
- Notice that at this point the mouse cursor changes to a small black square
- command-line stays empty
- click in viewport
- notice update of first material in material editor with lots of ‘m’-characters added at the begin of the name
there is more to this: with last material selected, do the objects select, copy and paste, then type M (mouse cursor changes to black square), then click. Note that the first material now reads the name of the last material with as many
m's prepended as you typed.
Here an animated GIF with the glitch:
note: interestingly enough the black square mouse cursor isn’t visible in the GIF - it shows when in the GIF the cursor briefly disappears while trying to write the m-character.
arguably better GIF. The input glitch is for any keyboard input, here I type
ExtractRenderMesh after the copy&paste, followed by ENTER. The enter appears to do the same as the mouse click in earlier reports/tests