First attempt at Excel-like data entry. Keyboard navigation with tab, return, shift-tab, shift-return, and arrow keys works as expected.

Shift-arrow highlights, although behavior is not Excel-like yet. In Excel, during shift-select the active cell remains fixed, and the shift-arrowing selects the active range rectangle of cells.

Typing replaces current content, although this is badly broken, since I'm catching key events, which is apparently a wildly inaccurate method of data capture (for instance, the keypad is totally NOT returning numbers).

The only mouse event captured right now is clicking to select a cell.

For future revisions I may use an absolutely positioned input or textarea layered on top of the chart to capture text input, and only use key events for tab, return, and arrows.