Fix Tree Mouse hover position

[Hilderin]

• Fixes Tree button click detection is off #102194

This PR should fixes the hovered, tooltip and click position for trees button.

The PR includes:

• A simplification of the _determine_hovered_item to use the _find_button_at_pos method which tried to do exactly the same thing, aka finding the button at a position.
• The space used by the scrollbar was not correctly calculated. At first, I tried to simply add the missing scrollbar_h_separation but there's some calculations in _get_content_rect that manage a situation where the scrollbar is inside the panel margin (when theme scrollbar_margin_right is >= 0). I simply used _get_content_rect directly like a lot of other places in the tree code. This fix was added in _range_click_timeout, gui_input, and _find_button_at_pos.
• The condition to check if the mouse position was hover a button was always off 2 pixels to the right because of a missing >= and a -1 needed because is a comparaison between a zero based position and a size. This fix was added in _find_button_at_pos and propagate_mouse_event.
• The margin area of the scrollbar was considered the last column and button.
• In RTL mode, the panel offset was calculated before the adjustment to pos.x in _find_button_at_pos causing an offset of a couple of pixels in RTL mode.
• Finally, I added -1 when adjusting the position in RTL mode in _find_button_at_pos to have the exact position. Ex: If the position is 99,0 and the size is 100,0 the actual position to use is 0,0. If the position is 0,0, the actual position to use is 99,0. I changed every place in the Tree code where these adjustments were present.

I tested in Window with the MRP from the issue and with different settings. I'm not familiar with the Tree control so I strongly suggest more test are done.

Note: There still some duplicate code between _find_button_at_pos and propagate_mouse_event but everything seems to work fine as is, I'm really not confident I can refactor this without any side effect, especially just before a new release.

godot.windows.editor.dev.x86_64_3rOzMy9UvI.mp4

[Hilderin]

It seems I missed little detail, in the editor Scene Tree, it's still off a couple pixels... I'll debug that...

[Hilderin]

I fixed the issue by reusing the _get_content_rect instead of trying to recalculate the correct scrollbar size.

But, I found out an other issue that the last button is considered hovered and is clicable from the margin around the scrollbar:

godot.windows.editor.dev.x86_64_r9luWwhb0f.mp4

I tested in Godot 4.3 stable and turns out that this behaviour existed in the version (minus the hover which did not exist in 4.3):

Godot_v4.3-stable_win64_HidwuJOb22.mp4

I fixed it anyway by adding a check for the position vs the content area (x_limit) in _find_button_at_pos and propagate_mouse_event.

Now:

godot.windows.editor.dev.x86_64_ZEPYRrybhU.mp4

[KoBeWi]

The original bug is still there:

godot.windows.editor.dev.x86_64_9tO5cv0WFE.mp4

Different buttons are hovered and clicked.

[Hilderin]

Indeed, there's was still some difference between propagate_mouse_event and _find_button_at_pos when the button were under the scrollbar or when the tree was scrolled to the right.

To prevent any difference between the two, I moved the commun parts in a new method called _find_column_and_button_at_pos. This method returns a new struct FindColumnButtonResult which contains all the info needed in propagate_mouse_event to work as before.

[KoBeWi]

Works correctly now.

[akien-mga]

Thanks!