public String getLastSceneComposerJson() {
        return (String) preferences.get("last-scene-composer-json", Utils.sanitizeFilePath(System.getProperty("user.home")) + "/");
    }
Checks every drawable path for existence. Errors are reported as a list
of DrawableDatas.
@return A list of all DrawableDatas that must have their paths resolved.
Returns an empty list if there are no errors.
core/src/com/ray3k/skincomposer/data/ProjectData.java