setting message doesn't trigger re-draw

have to call tick() afterwards to get it to show the message

The issue is about the `set_message` method not triggering a redraw. Look at the `ProgressBar` struct and its `set_message` method in the source code. Examine how the drawing logic works, likely in a `draw` or `tick` method. The fix likely involves ensuring `set_message` calls the internal redraw logic or sets a dirty flag. Check existing tests for message setting and redraw behavior to understand the expected flow.

索引モデルが issue の本文から書いたものです。