See the attached screenshot. The lock screen is shown twice when two displays are overlapping (partial clone). The screenshots shows the screen layout, where the large screen (matching the dimensions of the screenshot) is the primary screen. And small portion in top left corner is what is visible on the second screen. And there is the second prompt for password, overlapping the first one. Reproducible: Always Steps to Reproduce: 1. Set the second screen to show portion of the primary screen. 2. Lock the desktop. Actual Results: See the screenshot. Expected Results: A single lock screen as if the second screen is disabled. $ xrandr Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767 eDP1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 280mm x 160mm 1920x1080 60.04*+ 59.93 1680x1050 59.95 59.88 1600x1024 60.17 ... DP1 disconnected (normal left inverted right x axis y axis) HDMI1 disconnected (normal left inverted right x axis y axis) HDMI2 connected 800x600+0+0 (normal left inverted right x axis y axis) 0mm x 0mm 1920x1080i 60.00 + 50.00 59.94 1920x1080 60.00 50.00 59.94 1280x720 60.00 50.00 59.94 800x600 72.19* 720x576 50.00 720x576i 50.00 720x480 60.00 59.94 720x480i 60.00 59.94 1360x768_59.80 59.80 VIRTUAL1 disconnected (normal left inverted right x axis y axis) $ lspci | grep VGA 00:02.0 VGA compatible controller: Intel Corporation Broadwell-U Integrated Graphics (rev 09) $ uname -a Linux 4.5.0-2-amd64 #1 SMP Debian 4.5.5-1 (2016-05-29) x86_64 GNU/Linux
Created attachment 100513 [details] The screenshot
Sorry, but that is an extreme corner case we cannot properly support without risking to jeopardize the security of the system. As there are two screens it creates two windows and they are positioned exactly on the output geometry. That's part of the security infrastructure that every screen is covered. This is the expected and wanted behavior. Detecting and adjusting for the situation here would require special handling in a security relevant area. There is a risk that this would result in the screen not covered at all. A risk which we cannot carry for a corner case. There might be a chance that just clicking the larger locker will raise it above the other one.
Clicking the larger locker does not bring it above the smaller one. But I guess you already found the solution: Make sure the smaller overlapping locker is below the larger and/or make sure the primary screen locker is above all other lockers. Anyway, the exactly same thing happens also with the full screen pager -- the desktop grid effect.
> Anyway, the exactly same thing happens also with the full screen pager -- the desktop grid effect. and probably a few other places. Your setup is violating base assumptions in many areas concerning multi-screen behavior.