IDEMPIERE-4536 Allow minor customizations in default theme (#382)

only include fragment/custom.css.dsp if the file exists

org.adempiere.ui.zk/WEB-INF/src/org/adempiere/webui/theme/ThemeManager.java

@@ -19,6 +19,7 @@ import org.adempiere.webui.apps.AEnv;
 import org.compiere.model.MClientInfo;
 import org.compiere.model.MImage;
 import org.compiere.model.MSysConfig;
+import org.compiere.util.CCache;
 import org.compiere.util.Env;
 import org.compiere.util.Util;
 import org.zkoss.image.AImage;
@@ -146,7 +147,26 @@ public final class ThemeManager {
 			return null;
 		}
 	}
+
+	private static final CCache<String, Boolean> s_themeHasCustomCSSCache = new CCache<String, Boolean>(null, "ThemeHasCustomCSSCache", 2, -1, false);
 	
+	/**
+	 * @return true if custom css exists
+	 */
+	public static Boolean isThemeHasCustomCSSFragment() {
+		String theme = getTheme();
+		Boolean flag = s_themeHasCustomCSSCache.get(theme);
+		if (flag != null)
+			return flag;
+		if (ThemeManager.class.getResource(ITheme.THEME_PATH_PREFIX +  theme + "/css/fragment/custom.css.dsp") == null) {
+			flag = Boolean.FALSE;
+		} else {
+			flag = Boolean.TRUE;
+		}
+		s_themeHasCustomCSSCache.put(theme, flag);
+		return flag;
+	}
+
 	public static boolean isUseCSSForWindowSize() {
 		return "Y".equals(Env.getContext(Env.getCtx(), ITheme.USE_CSS_FOR_WINDOW_SIZE));
 	}	

org.adempiere.ui.zk/WEB-INF/tld/web/idempiere-util.dsp.tld

@@ -39,4 +39,15 @@
 	Clean all ampersand from string
 		</description>
 	</function>
+	
+	<function>
+		<name>isThemeHasCustomCSSFragment</name>
+		<function-class>org.adempiere.webui.theme.ThemeManager</function-class>
+		<function-signature>
+	java.lang.Boolean isThemeHasCustomCSSFragment()
+		</function-signature>
+		<description>
+	Returns whether theme has fragment/custom.css.dsp
+		</description>
+	</function>
 </taglib>

org.adempiere.ui.zk/theme/default/css/theme.css.dsp

@@ -124,4 +124,6 @@ table.z-vbox > tbody > tr > td > table {
 
 <c:include page="fragment/font-icons.css.dsp" />
 
-<c:include page="fragment/custom.css.dsp" />
+<c:if test="${u:isThemeHasCustomCSSFragment()}">
+    <c:include page="fragment/custom.css.dsp" />
+</c:if>