This does not reproduce in Sprint 21! Both Mac and Win (with slightly different recipes). Does not seem to be any file corruption -- just a refresh problem.

1. Open a longer file such as src/styles/brackets.less
2. Ctrl-End or Cmd-down to go to end of file
3. Select from EOF up to half the screen or so
4. Press Delete or Backspace

Results:
Huge block of unpainted screen at top of editor. It doesn't really matter how much is selected, but more makes it easier to see.

Mac Details:
Seems to require the EOF is part of selection

Windows Details:
EOF does not need to be part of selection. Needs to be last page of file so the text above selection fills in the page.