2020.2 broke Handles.Button registering click in sceneview while alt is being held.

Code (CSharp):

1.  
2. private void OnSceneGUI()
3.     {
4.         if(Event.current.alt)
5.         {
6.             if(Handles.Button(HandlePosition, Quaternion.identity, 2, 2, Handles.ConeHandleCap))
7.             {
8.                 Debug.Log("This Debug.Log will never occur");
9.             }
10.         }
11.     }
12.  

In 2020.2+, that code is failing to register the button click when alt is being held for the button to appear.

I believe it's because of a recent change Unity made to fix this bug:
https://issuetracker.unity3d.com/is...-rotation-when-mouse-hovering-over-the-button

I believe that whatever they did to fix that bug caused this unintended side effect. I could be wrong on that but the time lines up with when this started occurring. And the 2020.2 Patch notes state

• Editor: Fixed an issue where Handles.Button prevented Scene View navigation. (1250996)

And sceneview navigation is done via alt+clickdrag. So my assumption is that that change is what affected it.

From I believe 5.4 to 2020.1 this script has worked as expected, with it now not working in 2020.2+ It might be that you now need to assign a custom control ID to the GUIUtility.hotcontrol to override the sceneview navigation that now overrides the lack of a custom control ID for Handles.Button, but I don't know enough to comment on that.

Made bug report: Case ID: 1301950

 

I tried messing around with setting GUIUtility.hotControl and Event.current.Use() on certain events with some success, but not complete success. By setting the hotcontrol I could get the editor script to completely ignore the SceneView navigation Event which would let the Handles.Button trigger, but it was not reliable and I could not manage to return hotControl to SceneView Navigation after keyup because I am not sure how to get its controlID.

 

I am also running into this issue, a few plugins appear to have broken because of this change. I would be very interested in any solutions people have found.

 

Sadly my bug report was responded to that said the dev who made the fix says it is intentional and that sceneview navigation should override all editor scripts when pressing alt.

Which to me doesn't seem right given how many other built-in editor functions can get overridden via editor script, but I didn't argue. Especially since the button click still goes through visually when you press a Handles.Button holding alt, but the onclick just doesn't activate.

I'm convinced the dev is wrong but again it's easier for me to just change it from alt than to argue and wait for a fix.

 

Same here, I was using Ferr2D, holding alt with click function was delete point on terrain, it's not work after update.