HotStrokes: Word-Gesture Shortcuts on a Trackpad.

Expert interaction techniques like hotkeys are efficient, but poorly adopted because they are hard to learn. HotStrokes removes the need for learning arbitrary mappings of commands to hotkeys. A user enters a HotStroke by holding a modifier key, then gesture typing a command name on a laptop trackpad as if on an imaginary virtual keyboard. The gestures are recognized using an adaptation of the SHARK2 algorithm with a new spatial model and a refined method for dynamic suggestions. A controlled experiment shows HotStrokes effectively augments the existing "menu and hotkey" command activation paradigm. Results show the method is efficient by reducing command activation time by 43% compared to linear menus. The method is also easy to learn with a high adoption rate, replacing 91% of linear menu usage. Finally, combining linear menus, hotkeys, and HotStrokes leads to 24% faster command activation overall.