Fix EditorSpinSlider bad mouse position and zoom issues (Fix #46632 & #46708)

[jmb462]

Fix #46632 & #46708 issues

As described in the issue mentionned, EditorSpinSlider grabber was not at the correct position when GraphEdit zoom wasn't set to 1.

Also the mouse position when releasing the grabber was incorrect.

Solution :

Scale in now applied when calculating the grabber position.
I use get_global_transform_with_canvas().get_scale() to get the scale.

Also, the visual size of the grabber is now correctly scaled.

Finaly, the mouse position when we released the grabber is set correctly at the grabber position.

Zoom fix :

(Note that this gif has been captured before the mouse fix was added, so the mouse position is weird but now it's ok)

Mouse position fix :

Before :

After :

[gongpha]

In the master branch, EditorSpinSlider's grabber still bugged when dragging on. If compared with 3.2, when dragging on grabbers, They should highlight and the returned value could same as the actual mouse position. Not like when dragging on spinbox space. (See #44318)

[jmb462]

@gongpha Sometimes, there is a factor applied : the mouse relative motion doesn't match with the visual grabber moves. I suppose that's why mouse is now captured to hide the divergence between knob and real mouse pointer.
I think it's more a feature than a bug.

[gongpha]

@jmb462 I meant an actual slider grabber is currently not working (it's broken earlier). The changes you made are for spinbox grabbing. That meaning it's able to start grabbing anywhere inside the box.

In the picture, The mouse position returned to the grabber position. Including when start grabbing on outside the slider.
Did you expect this ?

[jmb462]

I think that :

1. the mouse cursor should reappear on the grabber only if the grabber was used and reappear at the same point he desappear if the grabber wasn't used ?

2 ) The round grabber should be visible while dragging

I will try to modify in that way.

[gongpha]

I think #44334 (like #44318) should be fixed first. Then the slider will work perfectly.

Also, IMHO, It doesn't need to return a mouse position to grabber position. The slider will do its job if it works. ^^

[jmb462]

As a top_level control, it doesn't inherits from its parents' transform. It may cause the problem with zoomed GraphEdit.
This part is a feature of "top_level" property so I think the scale of the grabber need to be fixed with my proposal.

For the second part (mouse position / grabber visibility), this should return to normal if #44334 is fixed.

I think I should close this PR, and repost a PR for just fixing #46632. (done => PR #46943)

No idea how to fix #44334.

[jmb462]

Closed this one and open the new PR for grabber zoom only #46943