Missing redraw if only cursor position changes

[Calonca]

When only the cursor is drawn in a new position and no other text changes are made the displayed output does not get updated and the cursor stays in the previous position.

In this example below in the text field the cursor does not move when arrow keys are pressed unless the position is shown on the screen. The position text update forces the redraw.
If the arrow keys are pressed when the position is not active and the position is then activated by pressing space the cursor will jump to the intended position.
https://github.com/Calonca/ratzilla/tree/fix/cursor-movement-invisible-example/examples/cursor_test

Forcing a redraw is a workaround for the issue
72753a6

So the problem might be due to a null diff and a skipped redraw when only the cursor position is updated.

[junkdog]

thanks for reporting, i'll take a look - is the behavior the same for all backends?

[Calonca]

Thank you for the contributions.

For me in the cursor_text example the cursor is shown only with in the webgl2 backend. The other backends don't render the cursor so I was not able to check if the issue was present.

Instead in the text_area example the cursor is shown in the webgl2 and dom backend but not in the canvas backend.
The problem is not present in this other example. The example uses https://crates.io/crates/tui-textarea

By using https://crates.io/crates/tui-textarea in the cursor_text example instead of manually setting the cursor position the redraw is also correctly handled.