Comment 21 for bug 1650977

Because of the pretty lengthy discussion and so scattering of the multiple bugs/flaws we have found , I have made a sum up of what have we found until now.
I hope this makes picking up the bugs easier for whoever will be tasked with solving these issues.

1) Showing the icons on the primary screen only works if your primary screen is positioned as the left screen in System settings - Display.
This appears to be a underestimated problem that shows up when your Primary screen is physically positioned at the right and you adjust the position accordingly in “System settings – Display”.
This is a software problem and not a driver problem so it should be related to all multi monitor setups!
This should be solved as a separate bug.
2) "Show desktop icons on all monitors" is a much misunderstood function and part of that is because it does not work correctly because after a reboot the icons on the second monitor do not show after a reboot when set to "Show desktop icons on all monitors".
If you switch from "Show desktop icons on all monitors" to "Show desktop icons on primary monitor only” and back again to "Show desktop icons on all monitors" the icons appear again.
This is an error in the functionality and the cause of this bug.
If your primary monitor is positioned as the right monitor in “System settings – Display” you then get the missing icons problem.
This should be solved as the primary monitor is not always the left one.
In my case my secondary display is a 55” TV and is placed at the left and so my primary monitor is placed at the right.
Physically moving the TV to the right is not an option in my case but you do want the monitor position in “System settings – Display” to reflect the physical position of your setup so your mouse movement is logical.
3) Then there is a third problem that is influencing your Multi monitor experience.
The sequence in the hardware detection of your video output ports is influencing the icons on your desktop. At this moment for multi monitor setups to work well, the primary monitor should be positioned as the left screen in “System settings – Display” and should be on the first detected display port.
Only then the desktop icons show directly after a reboot or a log off and log on action.
4) The snap to grid of the desktop icons doesn’t work well.
The icons do not snap to the closest position but snap to the NEXT closest position.
The snap to grid appears to work from top to bottom and from left to right.
That means that when you try to position an icon at the bottom of the screen but position it just to low or just a bit to far to the right, then the icon will move to the next column at the top of the screen.
If this is a bug or not can be argued but it is at least undesirable behavior.
5) What is a bug in my eyes however is that there seem to be 3 or 4 vertical grid lines per icon height.
This seems to be hard coded and my advice should be to make horizontal and vertical grid lines adjustable from the System settings screen in 1 to 2 times the icon height. This way you can adjust the space between icons to prevent text overlap with longer icon descriptions and adjusting the space between icons when changing the icon size.
The the horizontal direction the columns seem to be correctly about the width of an icon.
6) There is no snap to grid blocking if the space is already occupied by another icon.