Enabling both trim_trailing_white_space_on_save and save_on_focus_lost leads to somewhat unpleasant behavior. For example, I'm editing a python file and I've got the cursor on a new line (properly indented to 3-4 tabs/4-space groups), or I've just started writing an assignment (with something like foo = <cursor> in the editor). If I switch to some other app and then switch back, cursor will jump to the beginning of line or erase whatever spaces I had at the end of current line, and then I'll have to reinsert these spaces manually. This is even more annoying if this is the last line and ensure_newline_at_eof_on_save is also set — the cursor is forcibly moved to the next line whenever you cmd-tab. I understand that ST doesn't support virtual whitespace (hopefully it will do in the future), but perhaps you could add some hack to fix this specific issue?