Comment 4 for bug 48371

After some digging and playing with the settings, it looks like this bug depends on the GTK style settings in the user preferences.
The default setting (System Settings->Appearance->GTK Styles and Fonts) is to use the KDE styles. This setting results in uncleared tiles appearing the same color as cleared tiles (white for me). Use of the "QT" Style also results in all white tiles. If the preference is switched to use "Raleigh" (Use another style->Raleigh, **and** GMines is restarted), however, the uncleared tiles appear blue and the cleared tiles appear white. I took some screenshots showing my setup; as soon as I figure out how to load the pictures I'll add them here.