White flash when coming back from "Show desktop"

[mahfiaz]

1. Use dark backgroud for your slide and desktop, black would work fine.
2. Send something live
3. Press D repeatedly to see how every time live window is recreated it flashes white.

Some probably flawed ideas how to prevent this:
Send first extra short webpage with only background information (when using images it would still take some time and might not work so good)
Start window minimized and show it after it has finished rendering
Start window somewhere else and move it to the right position after it has finished rendering

Or maybe this is not fixable. But at least we gave a thought :)

[Joakim Lundvall (jocke-lundvall)]

I don't know if this is the same bug but if I set screen to blank with "." and then starts a libre office presentation from service manager it will be rendered on screen for a split second before overdraw with black again.

[Ken Roberts (alisonken1)]

Shows on KUbuntu 14.04 as well

[Ken Roberts (alisonken1)]

When I use "." to hide live, I also get the following:

2014-10-21 16:20:21,543 openlp.core.ui.maindisplay.MainDisplay DEBUG Entering hide_display
2014-10-21 16:20:21,543 openlp.core.ui.maindisplay.MainDisplay DEBUG hide_display mode = 1
2014-10-21 16:20:21,544 openlp.core.common.registry ERROR OpenLP Error trace
   File ./openlp.py at line 44
         called main()
   File /home/ken/program/python/openlp-bzr/trunk/openlp/core/__init__.py at line 332
         called sys.exit(application.run(qt_args))
   File /home/ken/program/python/openlp-bzr/trunk/openlp/core/common/openlpmixin.py at line 61
         called return func(*args, **kwargs)
   File /home/ken/program/python/openlp-bzr/trunk/openlp/core/__init__.py at line 160
         called return self.exec_()
   File /home/ken/program/python/openlp-bzr/trunk/openlp/core/common/openlpmixin.py at line 61
         called return func(*args, **kwargs)
   File /home/ken/program/python/openlp-bzr/trunk/openlp/core/__init__.py at line 98
         called result = QtGui.QApplication.exec_()
   File /home/ken/program/python/openlp-bzr/trunk/openlp/core/common/openlpmixin.py at line 61
         called return func(*args, **kwargs)
   File /home/ken/program/python/openlp-bzr/trunk/openlp/core/ui/slidecontroller.py at line 928
         called self.blank_plugin()
   File /home/ken/program/python/openlp-bzr/trunk/openlp/core/common/openlpmixin.py at line 61
         called return func(*args, **kwargs)
   File /home/ken/program/python/openlp-bzr/trunk/openlp/core/ui/slidecontroller.py at line 985
         called self.service_item.name.lower(), [self.service_item, self.is_live, hide_mode])
   File /home/ken/program/python/openlp-bzr/trunk/openlp/core/common/registry.py at line 156
         called trace_error_handler(log)
   File /home/ken/program/python/openlp-bzr/trunk/openlp/core/common/__init__.py at line 59
         called for tb in traceback.extract_stack():
2014-10-21 16:20:21,545 openlp.core.common.registry ERROR Event songs_blank called but not registered

[Tim Bentley (trb143)]

The stack trace is different and should be ignored.

I am unable to reproduce the flashing on my machine. It may be display driver specific.

Question why would one press D quickly many times.

[Raoul Snyman (raoul-snyman)]

I can't reproduce this.

[Ken Roberts (alisonken1)]

Confirmed on KUbuntu 14.04 w/updates
OpenLP 2.1.3

When switching to live, looks normal
When switching to/from black icon in OpenLP, looks normal
When switching from live to desktop view, looks normal
When switching from desktop view to Live - white flash, then live shows

[Ken Roberts (alisonken1)]

Dell laptop w/intel chipset using hdmi output to second screen.

[mahfiaz (mahfiaz)]

Tim, quickly pressing just D makes it more visible, it might not happen on every try.

Happens on my T420 with Intel graphics with 2.0.4 (unfortunately upgrade path is blocked by incompatible dependencies and I cannot test 2.1.x right now). I happen to be on Linux Mint Debian Edition using Cinnamon (clone of gnome-shell, uses compositing).

[mahfiaz (mahfiaz)]

I haven't seen this in a few years. I think it's time to close it.