Snowball translation window:
Resize window: Drag any edge or corner with mouse
Move window: Alt-M

Selection keys
Move selection point to next/previous source word: Right/left arrow keys
Select next/previous target for selected source: Up/down arrow keys or single-click
Replace selected source in Word document with selected target and save to memory: Enter, double-click
Extend/shorten selected source: Ctrl-Shift+right/left arrow keys

Editing translations
Open selected target for editing: F2, single-click, or just start typing to overtype
Copy selected source to clipboard: Ctrl-Shift-C
Paste clipboard contents into target (when target is not open for editing): Ctrl-Shift-V
Paste clipboard contents into target (when target is open for editing): Ctrl-V
Delete selected translation: DEL or right-click>Delete
Undo previous translation: Ctrl-Shift-Z (will not work on previous sentence)
Insert comma or semicolon after last word before insertion point: Alt+,/Alt+;

Operating modes:
Automatic/Manual mode: Options > General
Word-by-word/Whole sentence mode: Options > General

Display:
Colors: Options > Colors