[themes] Themes don't support background styling #3429
Description
.tmTheme files allow specification of background colors which don't seem to be supported, for example:
<dict>
<key>name</key>
<string>Separator</string>
<key>scope</key>
<string>meta.separator</string>
<key>settings</key>
<dict>
<key>background</key>
<string>#E0E0E0</string>
<key>foreground</key>
<string>#373B41</string>
</dict>
</dict>This is especially problematic for themes that attempt to invert background and use a similar foreground to the text view's background color (#2158)