Windows only

What happened:
Due to unity starting in elevated mode, files (such as images) cannot be dragged from the file explorer to the project view

How we can reproduce it using the example you attached:
1) Install 2017.3.0f1 on Windows and tick "Launch Unity" before finishing the installation
2) New project or existing project
3) Open file explorer to a folder that contains an image file
4) Try to drag the image from the file explorer to the project view

Expected result:
The image can be dragged across and can be added to the project

Actual result:
The cursor becomes a circle-backslash symbol and the image cannot be added to the project