I have added 2 new features to Sketcher for convenience.
Tool panels are now open one at a time. Clicking one panel will close all other panels, to save on screen space and user effort. A pin button has been added to each panel, to lock panels in their current state (open or closed), independently of other panels. This hybrid approach should be a good compromise between tabs, for those who have small screens, and panels, for those who have large ones.
Drag scrolling is now implemented. Hold down the Space bar to use it. NOTE: Sketcher can't tell if you wish to enter a whitespace in the chat box, or if you wish to scroll the canvas, so you must click the canvas before you hit the Space bar!
UPDATE: I have added a small menu bar above the Canvas panel. The Save button has been replaced by a "Save As..." item in the File menu.