[DMenu|Script] Allow theme element updates from script.

Examples/test_script_mode_color.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+
+if [ "$*" = "quit" ]
+then
+    exit 0
+fi
+
+if [ "$@" ]
+then
+    # Override the previously set prompt.
+    echo -en "\0theme\x1felement-text { background-color: "$@";}\n"
+    echo "red"
+    echo "lightgreen"
+    echo "lightblue"
+    echo "lightyellow"
+    echo "quit"
+else
+    echo -en "\x00prompt\x1ftesting\n"
+    echo -en "\0urgent\x1f0,2\n"
+    echo -en "\0active\x1f1\n"
+    echo -en "\0message\x1fSpecial <b>bold</b>message\n"
+
+    echo "red"
+    echo "lightgreen"
+    echo "lightblue"
+    echo "lightyellow"
+    echo "quit"
+fi

source/modes/script.c

@@ -138,6 +138,11 @@ static void parse_header_entry(Mode *sw, char *line, ssize_t length) {
     } else if (strcasecmp(line, "data") == 0) {
       g_free(pd->data);
       pd->data = g_strdup(value);
+    } else if (strcasecmp(line, "theme") == 0) {
+      if (rofi_theme_parse_string((const char *)value)) {
+        g_warning("Failed to parse: '%s'", value);
+        rofi_clear_error_messages();
+      }
     }
   }
 }