Eyedropper magnifier leaves a trail on the screen

[Gear maker]

This is a weird one.  I only include it because it just isn't the way it should be.  I wasn't able to reproduce it in MAS.

 

It only happens in Separated Mode.

 

I had loaded a .jpg into AD because I wanted to use the same color in a project.  I drug the eyedropper across the screen and it left a trail behind it changing the color of everything it flew over.  I also found that the brush tool, if the brush size is over a certain amount does it also.

 

In the attached video it first shows the magnifier of the eyedropper as it passes over the jpg and even areas that are just the blank AD screen show the change.  Releasing the mouse button erases the trail.  Then I switch to the Brush tool, without pressing the mouse button.  It starts with a brush that is 60.5 px and doesn't leave a trail.  Then the brush enlarges to 69.5 and it leaves a trail.

 

The trail stays on the screen.  Switching to another tool erases the trail.

 

I found that when zoomed to 150% it left a trail when the brush got bigger than 41 px.  The more I zoom the smaller the brush size needs to be to leave a trail, with a 500% zoom it does it with a 12.5 px brush.  On my screen the brush size has to be a circle of about 1/2 inch to cause it.  Anything smaller there isn't a trail, anything larger there is a trail.

 

Any ideas?

 

27" iMac late 2009 Yosemite

AD Beta 1.0.202013