The background color is only set when MiniBrowser is launched without arguments. This regressed when tabs support was added.
Created attachment 367935 [details] Patch
Attachment 367935 [details] did not pass style-queue: ERROR: Tools/MiniBrowser/gtk/BrowserTab.h:57: browser_tab_set_background_color is incorrectly named. Don't use underscores in your identifier names. [readability/naming/underscores] [4] ERROR: Tools/MiniBrowser/gtk/BrowserTab.c:607: browser_tab_set_background_color is incorrectly named. Don't use underscores in your identifier names. [readability/naming/underscores] [4] Total errors found: 2 in 5 files If any of these errors are false positives, please file a bug against check-webkit-style.
Please add these files to the style checker whitelist.
Committed r244583: <https://trac.webkit.org/changeset/244583>
<rdar://problem/50159645>