Show native documentation in a popup (in Script Editor)

[echebbi]

Describe the project you are working on:
Mostly following tutorials to discover Godot.

Describe the problem or limitation you are having in your project:
I can't check the documentation of native classes/functions as I read code. The closest feature is CTRL + click but:

• it opens the whole documentation in another tab, and having to systematically switch back is really inconvenient,
• it requires the mouse.

Describe the feature / enhancement and how it helps to overcome the problem or limitation:
The ScriptEditor could show a popup displaying the documentation of the selected element. This popup could be shown:

• on hover, when the cursor stay above an element without moving for, say, more than one second,
• when a specific keyboard shortcut is hit.

This proposal is highly related to #408 but addresses a complementary use case.

Describe how your proposal will work, with code, pseudocode, mockups, and/or diagrams:
Most IDE have such a feature, GDScript for VS Code does it as follows:

If this enhancement will not be used often, can it be worked around with a few lines of script?:
This enhancement would definitely be often used:

• it has been requested in Godot's main repository: Code editor improvement: quick documentation godot#27607
• the VSCode extension supports it: Enable scripts to generate XML API documentation for the editor's GUI #177 (comment)

Is there a reason why this should be core and not an add-on in the asset library?:
I believe that it's a feature that would benefit to everyone and which should be embedded in Godot by default. That being said, since the VS Code extension already supports it I suppose that it may be possible to implement it as an add-on.

[Calinou]

Closing in favor of #1393, as the author of that proposal is developing a working implementation.