Reproduction steps:
1. Open attached "New Unity Project 79" project.
2. Open "1" scene.
3. Open "Window > Animation" tab.
4. Select "Main Camera" game object in the Hierarchy.
5. Click "Add Event" button several times.

Actual result(GIF attached):

• "Edit Animation Event" doesn't open and flashes for a split second.

Expected result:

• "Edit Animation Event" is opened(http://docs.unity3d.com/Manual/animeditor-AnimationEvents.html).

OR

• "Edit Animation Event" is not opened and doesn't flash.

Note:

• If issue is not visible in the GIF, download it. Browser playback may be too slow to show flashing frames.