During install and oem-firstboot, the header bar at the top of the screen in Ubiquity is twice as tall as it should be on hidpi screens (looking like two normal sized header bars stacked on top of each other), and the blue a11y icon is double sized.
This looks obviously incorrect and ugly and makes a bad first impression on users installing Ubuntu on a hidpi laptop or customers of Ubuntu OEMs booting new machines for the first time. Arstechnica commented negatively on this in their review of Dell's XPS 13: http://arstechnica.com/gadgets/2017/01/dells-latest-xps-13-de-still-delivers-linux-now-embraces-svelte-hardware/
Users of the Dell XPS 13 are affected as well as users of other brands of laptops with hidpi screens. System76 is temporarily carrying a patched version of Humanity to work around this bug.
The a11y icon is double-sized because the version of Humanity shipping in Ubuntu doesn't support @2 hidpi scaling, which results in the header bar doubling its height. Because the header bar is drawn with CAIRO_PAD_REPEAT, the gradient is repeated so it looks like two bars stacked one on top of the other. The fix to the Humanity icon theme adds @2 hidpi support, which shrinks the icon and restores the header bar to its normal height.
1. Grab an Ubuntu iso and proceed to install (not "try") Ubuntu on a computer with a hidpi screen.
2. Note the double-sized header and icon during install.
- Using an iso with a fixed version of Humanity, the header and icon should look normal.
1. Grab an Ubuntu iso and do an oem-install on on a computer with a hidpi screen.
2. After installing, click the launcher icon to "Prepare for shipping to the end user" and reboot.
3. During oem-firstboot, note the double-sized header and icon during install.
- To test the fix, install a fixed version of humanity before preparing the system for the end user.
This patch affects the look of anything using the Humanity icon set. The look of Nautilus, and many other GTK apps will be affected. This is not a regression but fixes another bug and resolves a discrepancy between rendering of icons on hidpi screens vs lowdpi screens.
The biggest risk for regression comes from the off chance that there is an error or omission in the index.theme files. Comparing icons on a broad range of applications and systems should catch this class of issues. If any issues with icons are found, check there.