Q: Bug: Dotted line dragging along with the mouse pointer

It is not a hardware issue, more to a driver issue as this doesn't happen on 10.10.5.

I have been doing some extensive testing as we have about 2000 Mid-2012 Macbook Pro, this problem can be duplicated under the following conditions on 10.9.x and 10.10:

- Using mDP to VGA adapter (Apple or aftermarket)

- Connected to a VGA monitor/projector that has a higher resolution than the built-in notebook display

- Unit was put to sleep via closing the lid or via the Apple menu AND THEN the mDP to VGA adapter is removed

Under the 3 conditions, I am able to duplicate this problem. I suspect it is a driver issue where the computer does not know the display adapter is removed, and is keeping the mouse cursor resolution as the projector.

This problem can usually be fixed by resetting the PRAM and SMC; and will not occur if using DVI or HDMI.

At OS X 10.11.2 the problem is still present for a macbook pro 2012. Strange that Apple still hasn't updatet it yet.

I am having the same problem with El Capitan.  It is REALLY bad when it occurs during video editing with FCPX.  The whole screen gets pixelated with horizontal and vertical lines.  Only a restart has been able to clear it thus far.

I'm having same issue as everyone else with the mystery dots & lines coming up.

I'm using Mavericks with Chrome Browser. Here's the thing: it only occurs for me when using Chrome.

No problems when using Safari, or in Finder or any other program, just Chrome. I've tried turning off

all extensions in Chrome - no change. Sure would be nice to get this resolved.

Anybody else seeing a connection to Chrome on this issue?????

Cheers, Ted

P.S. I'm using a Mac Mini 2012

Ted, THANKS for posting this. You are right....it only happens in Chrome for me as well!  I tried Firefox and it doesn't happen at all. I have a 2010 13" MBP, and this problem popped up about a month ago. Thought my video was on it's way out (I even did a back-up just in case it was going to die). All the posts regarding hooking up to externals didn't relate to me; glad I kept reading and found your post! Thanks again!

Nancy

I guess misery does love company.  I have had this problem for several years but could never find anyone else with the problem. I also have a early 2013 Macbook Pro that I've used daily for years.  I use a Thunderbolt display at my desk and it never occurred to me that it was related to this display (since I use it almost every day) but I will try the recommendations to not unplug while asleep and see if it fixes it.  It definitely occurs even if I'm not connected to a VGA projector as I only do that once or twice a week.  Like others have said this laptop has it's OS upgraded regularly, now on El Capitan and none of the OS changes have impacted this problem.

The main issue is that it is not only hashed - but there are applications where the mouse does not work properly when in this configuration - until I restart the computer.

This happens to me all of the time, you just have to turn off the projector and close the laptop, before you unplug the VGA cable. It goes away with that. Sometimes you just have to close the laptop and then pull out the cord, but the above steps always work.

Macbook Pro, 2014ish, updated to El Capitan (10.11.6) but problem persists.  In the absence of a bug-fix, any advice on resetting cursor without restarting the whole machine would also be helpful!

I'm over about 3000 devices, majority of them Mac computers. This was an issue for about a year, until finally the connection was made as to why this was happening. It appears that when your projector adapter is plugged into your computer and you close the lid while it is still plugged in, these annoying lines appear right below the arrow. To avoid this issue, you simply need to unplug the adapter to your computer before closing the lid. By restarting the computer, the lines will go away. This only happens with computers that were manufactured around the 2010 - 2012 years. I don't know if this problem still exists with newer computers, since the majority of these computers now connect via appleTV.

Why it exists: When your computer is plugged in with the video adapter and you shut the lid. This problem with occur. To avoid this issue, simple unplug the adapter before closing the lid.