Fix bottom panel sizing with multiple options

[Giganzo]

Fixes: #95681

Did see this issue a while ago and thought it looked interesting, as I needed to create something similar in gdscript and if a version could be made for the editor.

I did now see there is PR for this already. Haven't looked how it is implemented or tested it.
If not used in its entirety maybe something here can be useful or combined in to a PR.

Features:

I first made a version with < prev and next > buttons. But decided to remove them to save space in the bottom panel, as the popup menu gives you a good overview of all the options.

Before:

After (looks the same):

Compact

Default:

Light:

Oled:

Resizing and scrolling between options:

You can speed up scroll by holding alt key.

Screencast_20241123_091418.webm

Scrolls to clicked option:

Screencast_20241123_091707.webm

Scrolls to popup menu selection:

Popup only shows buttons visible in the bottom panel.

Screencast_20241123_092159.webm

Scrolls to the editor opened by events such as clicking on a node in the tree:

Screencast_20241123_092408.webm

[AThousandShips]

This won't work, you should use an ObjectID instead if you need to handle freed objects

get_validated_object only makes sense for a Variant created from a valid pointer

[Giganzo]

Thanks, how would I do that?

[AThousandShips]

You would get the ObjectID using get_instance_id and then fetch the object with ObjectDB::get_instance

[tetrapod00]

For testing, I re-uploaded the two extreme MRPs from the issue for convenience:

• Many small bottom panel tabs (made by @JekSun97): mrp-bottom-panel-many-small.zip
• Few large bottom panel tabs, made by me: mrp-bottom-panel-few-big.zip

This PR handles both of them just fine:

I'm not sure why, but in the Many Small MRP, this PR can't open any of the custom bottom panel tabs besides Test0. I'm not sure if that's a problem with this PR or with the MRP. These MRPs are not necessarily robust implementations of bottom panel plugins; they mostly exist as proof of concept of the problem existing.

godot.windows.editor.x86_64_CxssMxSWXO.mp4

---

So the really bad cases seem solved by this (once the issue with Many Small is solved). I also tested casually with a more normal workload using only built-in bottom panels, and it works as expected.

Is it possible to have the popup appear so the base is aligned with the top of the three dot button, rather than covering it?

Other three dot buttons spawn their popups directly below the button, they don't cover the button:

Resolved (will do a review later)

[Giganzo]

Is it possible to have the popup appear so the base is aligned with the top of the three dot button, rather than covering it?

Should open like this now

[tetrapod00]

The last editor artifact is broken for me on Windows 10:

Edit: If I spam click on it, it works correctly. This might be an unrelated bug, it seems familiar.

Yep, it's #99581 or something similar.

[Giganzo]

The last editor artifact is broken for me on Windows 10:
Yep, it's #99581 or something similar.

This didn't happen before?

Tried another approach with the button. Does this also trigger the above issue?

[tetrapod00]

godot.windows.editor.x86_64_MKuKmqzoKP.mp4

With this one, it's easier to get a correctly spawned popup, but it's still possible to get the bad version of the popup by spamming left click. I really suspect that this problem is unrelated to your PR, and is something similar to #99581. But I haven't reviewed your actual code and I don't know enough to, all I can do is test the functionality.

[Giganzo]

Thanks for testing! About the spam clicking, missed a bit of code in your latest test. Added it in now, hopefully it helps was told it prevented the issues of empty popup from one tester.

[KoBeWi]

Both this PR and #97878 use ScrollContainer, but the other PR uses side arrows instead of popup:

They make it more obvious that the buttons are scrollable. Also the popup isn't very useful, unless you have lots of buttons 🤔

[WhalesState]

We can have the menu button before the left arrow button, so why don't we combine both ? Also we can allow hiding the menu button in editor settings because i also don't like it, but others may see it useful.