Dilato: [Core]: User cannot simply drag an outside file to the folder that opened in Brackets.

[ZuoBaogang]

Problem: User cannot simply drag an outside file to the folder that opened in Brackets.

Test device: windows 10 64bit, Mac 10.12
Test build: 1.13.17657

Method:

1. Launch Brackets.
2. Drop and drag folder to Brackets.
3. Try to drag an outside file to the folder that opened in Brackets. (This file is not in the folder)
4. Observe.

Result:
User cannot simply drag an outside file to the folder that opened in Brackets.
The file will display in the working files panel, but cannot drag it to the folder that opened in Brackets.

Expected:
Outside file can be dragged to the folder that opened in Brackets normally.

Could you please help confirm whether this is a design? Thanks!