Fix time drawing color (was not being set)

The items showing the current time looked ugly on linux
when selected, since they were drawing in the leftover
blue color used for drawing the R-G-B box pattern.

examples/tree-custom-draw-items.cxx

@@ -97,6 +97,7 @@ public:
     X += 35;
     // Render the date and time, one over the other
     fl_font(labelfont(), 8);			// small font
+    fl_color(fg);
     const struct tm *tm = GetTimeStruct();
     char s[80];
     sprintf(s, "Date: %02d/%02d/%02d", tm->tm_mon+1, tm->tm_mday, tm->tm_year % 100);