Font rendering
It's a feature. Actually, it's not just the underline. For example, compare the 0
before and after: they're slightly different. By zooming the picture you can spot other subtle differences:
The subpixel rendering is not the same, as hinted by the changelog (bold emphasis mine):
Chrome 37.0.2062.94 contains a number of fixes and improvements, including:
- DirectWrite support on Windows for improved font rendering
- A number of new apps/extension APIs
- Lots of under the hood changes for stability and performance
A full list of changes is available in the log.
Source: Chrome Releases: Stable Channel Update
The change was aimed for the better, but it got mixed reactions because not everybody experienced a real improvement. Granted, the hardware and software combinations definitely play a major role here, so your mileage may vary.
Reverting back
If you don't like the changes, you can try disabling DirectWrite as a workaround:
Type or paste the following address in the Chrome address bar:
chrome://flags/#disable-direct-write
Turn off the DirectWrite feature. Restart the browser to apply the changes.
Note The steps above apply to version 37.0.2062.102
; newer versions might require a different approach. Since DirectWrite is only available in Windows Vista and later, the old GDI-based rendering engine could be removed entirely after XP support ends in April 2015.
Further reading