Gdevelop: Events are sometimes hard to drag

[PascalLadalle]

Describe the bug

When dragging a line of the events sheet, there is sometimes a position conflict that makes it impossible to know where the line will be dropped and it triggers a lag proportional to the duration of the position conflict. It seems this happens mostly when moving a line to a space higher in the list.

GDevelop 5platformer.json 2020-03-28 21-24-49.mp4.zip

To Reproduce

Steps to reproduce the behavior:

1. Open the platformer example
2. Grab an event somewhere down the list
3. Move it up one slot

Other details

Win10 64 bits, GD5 b89

[4ian]

Yep dragging events was never a good experience. I'd like at some point to rewrite the rendering of events and the drag'n'dropping in particular to have an approach similar to actions/conditions, with a line drawn at the position of the drop (and red if you can't drop).

[Wend1go]

Keyboard shortcuts would be handy too, like:
"CTRL" + "Arrow Up" = Move current event up by one position
"CTRL" + "Arrow Down" = Move current event down by one position
"CTRL" + "Arrow Right" = Move current event one level down in the subevent tree
"CTRL" + "Arrow Left" = Move current event one level up in the subevent tree

[gautamv95]

@4ian should we rely on some other 3rd party library for drag and drop behavior?
I looked at some of them, and I think they can provide better user experience than the current one, like keyboard shortcuts, better event handling, smooth animations, etc.

[4ian]

I don't think there is another 3rd party library doing that apart from react-sortable-tree.
Feel free to suggest one if you find - but I'm thinking of getting rid of react-sortable-tree and using just react-virtualized or react-window to do the virtualization.

[gautamv95]

I'll make a detailed list and let you know :)