Failure to add key and potential crash when adding keyframe to sequence through details panel

There is the potential for a crash when adding a key through the details panel. In cases where there is no crash the key is not added. 

1. Create a blueprint actor with the following component hierarchy DefaultSceneRoot>SkeletalMesh>CineCamera
2. Add the blueprint to a level
3. Create a sequence, and track the actor in it
4. With the actor selected edit the cine camera's focal length, but keep the cursor in the text box
5. Without deselecting the text box, click the add key button

RESULT

**A customer has reported a crash. When attempting to repro, I did not encounter a crash, but no key was added to the sequence. 

EXPECTED

No crash, and a new track, section and key are added to the sequence.

See attached UDN.