Smear cursor

[dmyyy]

Enables smear cursor shader on word movements. Tested with ghostty.

Fixes #14512

Edit: #16163 looks like a more forward-looking change in a similar vein.

[mthy41]

tested with kitty and worked

[senekor]

I'm using and enjoying this with Ghostty as well. Just one curiosity I noticed: The cursor renders a bit funny when it's placed on a tab character, which spans multiple cells. The upper cursor is the secondary one, the lower cursor is the primary one. The hardware cursor seems to render a single cell with a different color than the rest of the cells belonging to the tab character.

[senekor]

The problem seems to be that the "hardware" cursor doesn't get the theme's color for the cursor. This problem is most pronounced on light themes. A white cursor on white background is invisible. Should be a blocking issue IMO.

[waddie]

The problem seems to be that the "hardware" cursor doesn't get the theme's color for the cursor. This problem is most pronounced on light themes. A white cursor on white background is invisible. Should be a blocking issue IMO.

You’ll see this issue already with bar/underline cursors. Terminal cursors use the terminal’s foreground colour, Helix can’t theme them.

I believe this PR forces an unthemable cursor on all users, it will always draw the terminal cursor overlaid on Helix’s block cursor? That’s why #16163 introduces block-hardware, making it opt-in.