incrediBILL - 9:30 pm on Jun 18, 2012 (gmt 0)
That was quick.
It seems Opera 12 has the same DPI bug Chrome does and if you change the DPI from 96 DPI (default) to a higher setting like 120 DPI on your monitor, it doesn't handle the issue properly.
What happens is it thinks your viewport isn't the proper site and responsive CSS designs step-down and scale improperly. For instance, Twitter Bootstrap default code doesn't work out of the box as it thinks the main nav bar menu is too small and defaults to the drop down menu used on mobile devices.
Additionally, the main Opera window control buttons in the upper right corner for minimize, restore and close didn't work. Seen this all before on Chrome, which also can't handle windows DPI settings properly.
To fix it I had to change the properties for Opera when launched. I changed the compatibility mode setting to "Disable display scaling for high DPI settings" and VOILA! it functions.
But seriously folks, the average user would NOT know how to do this and shouldn't.
I'm shocked this hasn't been reported and fixed because anyone that's even remotely visually impaired, or uses really big hi-res monitors like I do, would probably have bumped the DPI above the default to get larger fonts. Firefox and MSIE get it right, this is not rocket science, this is basic GUI 101 kind of stuff.
I program windows, supporting this DPI issue properly is NOT hard!