Improve drag tab UI

[abey79]

What

This PR includes the following:

• Improves the UI of the dragged tab UI. Now it feels that the actual tab is being dragged, no some different looking thing. I applied 0.5 transparency on it.
• Styles the source and destination areas during the drag (actual styling TBD).
• Syncs with egui_tiles's master and includes a [patch], so a release of egui_tiles is needed soon after we merge this:
  • Moved dragged widget UI to Behaviour egui_tiles#16
  • Add tiles argument to Behavior functions egui_tiles#17
  • Make drag preview style customisable egui_tiles#18

TODO:

• fine tune overlay colours
• make overlay colours customisable in egui_tiles
• cleanup code (currently lots of redundancy)

Note

Do not review commit-by-commit, I messed my rebase/merges

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I have tested demo.rerun.io (if applicable)

• PR Build Summary
• Docs preview
• Examples preview

[abey79]

@martenbjork re: overlay effects while dragging. The current solution is the following:

• the source area is greyed out ("Alias.Color.Surface.Default.value" + 50% gamma)
• the destination area now uses white (50% for stroke, 10% for fill)

When the web demo is updated you might want to check it out and we can adjust these parameters.

[martenbjork]

When the web demo is updated you might want to check it out and we can adjust these parameters.

Nice! I think that works pretty well. Another small step towards making the UI feel like one big whole.

(The colors are a tad dull, but we can tweak it down the road when we've made some other design choices that might undull the UI. Regardless, that's on me 😀)

[martenbjork]

Now it feels that the actual tab is being dragged, no some different looking thing.

🥰💯

[Wumpf]

love it. Nice sideeffect that it also correctly distuinguishes between selected and unselected things being dragged - which seems weird at first but totally makes sense

[Wumpf]

very tidy, neat. I'd make it its own module but that's more of a taste thing I reckon :)