When editing a blend curve between two clips in Timeline, the Curve Editor disappears when clicking the canvas.
When the Curve Editor is floated, the behaviour is as expected, and the bug is not repro.

see attached CurveAddKeyBug.gif for bug repro
see attached Crurve_floating_expectedBehaviour.gif for expected behaviour

Embedded (non-floating) Curve Editor should have the same behaviour as when it is a floating window.

repro:
- open attached project
- select CubeTimeline and open Timeline
- select second clip
- in the Inspector, click the "Manual" blend In curve...
- click the canvas close to the curve itself...
bug: Curve Editor disappears
expected: Curve Editor does not disappear

this is a regression.
repro in...
Version 2019.3.5f1 (d691e07d38ef)
Timeline: 1.2.6

not repro in...
Version 2019.1.14f1 (148b5891095a)
Timeline: 1.0.0