For the love of everything that is holy, if in your design the icons for "Undo" and "Jump Backwards" are practically identical -- as in this font, where only th

For the love of everything that is holy, if in your design the icons for "Undo" and "Jump Backwards" are practically identical -- as in this font, where only the outline of the arrows differs -- , please, please "waste space" by adding text to the buttons. Don't make people discover which one's "undo" and which one's "discard the current screen" by trying the buttons out. That's not a friendly interface. An interface can be friendly without looking like a five year-old's doodle. A wall of text is intimidating and unfriendly, sure, but nobody older than eight is intimidated by having to read six or seven words.