Also tested on laptop
Broken: 2.79 RC1 519132b
Also broken in 2.78
Short description of error
Setting output X resolution to 4 disturbs some input nodes in compositing, making them hard to interact with.
Exact steps for others to reproduce the error
New project in 2.79 RC1
Go to compositing, enable compositing nodes,
Set Dimension X resolution to 4 in Properties -> Render. (4 is minumum)
Press f12 to render image.
Render layer node partially collapse in compositor.
(Apparently there is a use case for sub 4 pixels renders)
Other input nodes such as Image, Movie Clip, Texture, and Bokeh Image is affected by this.
Returns to normal when setting X resolution to 5 or higher and rerender.
A workaround is to double resolution then set percentage scale it down to 50%