don't need to confirm configuration change if we can verify mode was set
Submitted by William Jon McCann
Assigned to Desktop Maintainers
Link to original bug (#635564)
Description
Currently we prompt the user to confirm every configuration change. If the confirmation is not made then the configuration reverts to the last used.
This is somewhat annoying for the normal case where things work. Not only are the settings explicit apply instead of instant apply (something I think we should move towards) it makes me click a second time to keep them.
This is not even an elegant way to handle the case where the mode was not set correctly since the user most likely cannot see or select the "Restore Previous Configuration" button (especially since it isn't the default). And worse the display will be broken for 30 seconds without the user being able to see the apology/confirmation dialog.
It sounds like theoretically we should be able to query the device to determine whether the requested mode was actually used. This should allow us to not require the confirmation in the cases where it is set correctly.
The confirmation isn't needed for arrangement because if you see the settings window now you should still see it after arrangement (modulo compositor bugs). Except when arrangement also changes resolution and that should be covered by the mode verification already.
In cases where we can't tell, we can still display a confirmation dialog but we can change the wording to make it clear that automatic detection failed for this hardware.
When we can positively detect that a mode was not set correctly we can more immediately return to the working configuration and present an appropriate message to the user.
Much better all around I think.
Thanks to Adam Jackson for suggesting this.