Code Editor: Add documentation tooltips

[dalexeev]

• Depends on Fix connecting a signal with a double click is too difficult #95044.
• Closes Implement script editor description hint on hover a symbol/word godot-proposals#1393.
• Supersedes Implement script editor hover hint with description #63908.
• Supersedes GDScript Symbol Tooltip #80044.

[KoBeWi]

Tested again and it works great now. One major issue is that when moving cursor very slightly the tooltip will disappear, even if you move it over the same symbol. It will open again, but the frequent blinking is bothersome.

Also if you hover a symbol and then move the cursor far away, even outside script editor, the tooltip will still appear.

godot.windows.editor.dev.x86_64_i5Yg4ovIAM.mp4

[dalexeev]

Ready for testing/review.

• Depends on Fix connecting a signal with a double click is too difficult #95044.
• This would go well with Scripting: Fix script docs not being searchable without manually recompiling scripts #95821.
• It also makes sense to separate Ctrl+LMB functions. Say Ctrl+LMB - open the docs and Alt+LMB - open the code.

Along the way I noticed/fixed a few bugs in gdscript_editor.cpp, gdscript_docgen.cpp, and script_text_editor.cpp, but there are still some things that make sense to fix separately, as I'm afraid that this might be a significant refactoring (enums, FQCN).

Also if you hover a symbol and then move the cursor far away, even outside script editor, the tooltip will still appear.

Fixed, thanks.

One major issue is that when moving cursor very slightly the tooltip will disappear, even if you move it over the same symbol. It will open again, but the frequent blinking is bothersome.

I understand that Visual Studio Code does it better (the tooltip doesn't disappear until the mouse leaves the symbol), but I'd rather leave it as is for now. This is consistent with the behavior in the inspector and signal dock, and it's also the same as in Kate.

But most importantly, it's technically hard to do. The tooltip checks if the mouse has left the target. This works for simple controls, but not for Tree and CodeEdit, which consist of many visual parts that are not nodes. Also, TextEdit/CodeEdit allows you to get the symbol at a given position as a string, but has no API to get positional information so we can determine whether it was the same symbol or another such identifier on the same line.

I'd suggest leaving non-critical issues for later PRs, as I don't want to further affect unrelated parts of the engine. In my opinion, this is not a very critical issue, I tried to make it so that the tooltip does not interfere with keys, clicks, scrolling and text selection.

Another usability issue is that TextEdit finds a symbol outside the line:

But the same happens if you hold down Ctrl:

[KoBeWi]

Hovering over variable definition does not show a tooltip. It could be useful when using inference, so e.g. you can hover var something := method() and know the type of something at the source, without having to find its usage.

This is consistent with the behavior in the inspector and signal dock, and it's also the same as in Kate.

For some reason I find it more difficult to see tooltips in code editor than in the inspector. Maybe the minimum movement is too small?

[dalexeev]

Hovering over variable definition does not show a tooltip. It could be useful when using inference, so e.g. you can hover var something := method() and know the type of something at the source, without having to find its usage.

Looks like it's not implemented in the parser:

godot/modules/gdscript/gdscript_parser.h

Lines 1294 to 1298 in 19e003b

	COMPLETION_BUILT_IN_TYPE_CONSTANT_OR_STATIC_METHOD, // Constants inside a built-in type (e.g. Color.BLUE) or static methods (e.g. Color.html).
	COMPLETION_CALL_ARGUMENTS, // Complete with nodes, input actions, enum values (or usual expressions).
	// TODO: COMPLETION_DECLARATION, // Potential declaration (var, const, func).
	COMPLETION_GET_NODE, // Get node with $ notation.
	COMPLETION_IDENTIFIER, // List available identifiers in scope.

When I hover over the variable declaration identifier I get {type = GDScriptParser::COMPLETION_NONE, current_class = 0x0, current_function = 0x0, current_suite = 0x0, current_line = -1, current_argument = -1, builtin_type = Variant::VARIANT_MAX, node = 0x0, base = 0x0, parser = 0x0}.

This and some other issues with incorrect hints are material for future PRs.

For some reason I find it more difficult to see tooltips in code editor than in the inspector. Maybe the minimum movement is too small?

I can't reproduce it on Linux. I encountered this during development, but at some point the bug disappeared.

[KoBeWi]

Would be nice to update it with settings_changed signal.

[KoBeWi]

Suggested change

	// TODO: this is sometimes used directly as doc->something, other times as EditorHelp::get_doc_data(), which is thread-safe.
	// TODO: This is sometimes used directly as doc->something, other times as EditorHelp::get_doc_data(), which is thread-safe.

[KoBeWi]

Looks like the description can't be determined in complex code:

Even though Ctrl+Click jumps to the member and it has a description.

I assume this is related to #95821?
EDIT:
Yeah, I saved the script and it works.
EDIT2:
Interestingly, the tooltip also misses method's signature, but it's able to infer correct variable type from the method's return value.

[KoBeWi]

The base functionality works fine. I agree it can be improved later if needed.
I checked the code of editor and gui in the second commit and also looks ok.