Idk why this is still an issue in Rhino after all these years - the grasshopper window loses focus and all commands go to the Rhino command line. See here:
Keystrokes in GH end up in Rhino command line - Grasshopper - McNeel Forum
Have the same -delete glitch. But I just found a pattern, which solves the problem for me. (Windows7 x64 Rhino 4)
- Click - Show desktop button on taskbar (Rhino and Grasshopper window minimizes)
- Click one more time - Show desktop button (Rhino window restores, but Grasshopper window is not)
- Just double click Grasshopper window to maximize it, and the problem disappears.
https://www.grasshopper3d.com/xn/detail/2985220:Comment:604100