add missing nextrow character for options rows

Themes/_fallback/Fonts/_16px fonts.ini

@@ -5,4 +5,4 @@
 # have them pulled in for every 16-pixel font.
 # xxx: we don't have 16px japanese or korean fonts
 [main]
-import=_Thai 16px,_misc 16px,_game chars 16px
+import=_Thai 16px,_misc 16px,_game chars 16px,_ui chars 16px

Themes/_fallback/Fonts/_20px fonts.ini

@@ -10,4 +10,4 @@
 
 # The characters in _game chars 16px are actually very large;
 # they'll look fine here, too.
-import=_japanese 24px,_korean 24px,_game chars 16px,_misc 16px
+import=_japanese 24px,_korean 24px,_game chars 16px,_ui chars 16px,_misc 16px

Themes/_fallback/Fonts/_ui chars 16px.ini

@@ -0,0 +1,14 @@
+# The characters in this font are actually much larger than 16 pixels.
+# The "16px" indicates what size uppercase letter this font is meant
+# for, not necessarily the actual size of the characters.
+
+[main]
+0=24
+
+# Don't load this font grayscale.
+TextureHints=16bpp
+
+Top=8
+Baseline=24
+
+map nextrow=0