I just started using the UE4 and the version should be new. The problem I encountered is I can’t drag my class file over the viewport which would lose the window I just selected. Like the picture, if I drag the file like the Red direction, the item I just selected will disappear and gives me the window below. To avoid this problem, I have to drag the file as the Blue direction which adds the file.
I checked some tutorial video and I found that when they are dragging over the viewport, a small redcross will appear without losing the focus. However, I see they are dragging a blueprint instead of class. Is there any special configuration or hot keys I need to use to solve this?