Show text validation errors if not in multiselect mode (#2133)

Change-Id: Iadbfae002175a409b928f5c7e705c85cdb70566d

appinventor/appengine/src/com/google/appinventor/client/editor/youngandroid/YaFormEditor.java

@@ -763,6 +763,7 @@ public final class YaFormEditor extends SimpleEditor implements FormChangeListen
             break;
           }
         }
+        newProperties.getProperty(name).getEditor().setMultiselectMode(true);
         newProperties.getProperty(name).setValue(sharedValue);
       }
       selectedProperties = newProperties;

appinventor/appengine/src/com/google/appinventor/client/widgets/properties/PropertyEditor.java

@@ -14,6 +14,8 @@ import com.google.gwt.user.client.ui.Composite;
  */
 public abstract class PropertyEditor extends Composite {
 
+  private boolean multiselectMode = false;
+
   /**
    * Property being edited by this editor.
    */
@@ -46,4 +48,12 @@ public abstract class PropertyEditor extends Composite {
   public void refresh() {
     this.updateValue();
   }
+
+  public void setMultiselectMode(boolean multiselect) {
+    multiselectMode = true;
+  }
+
+  public boolean inMultiselectMode() {
+    return multiselectMode;
+  }
 }

appinventor/appengine/src/com/google/appinventor/client/widgets/properties/TextPropertyEditorBase.java

@@ -152,11 +152,13 @@ public class TextPropertyEditorBase extends PropertyEditor {
       validate(text);
       property.setValue(text);
     } catch (InvalidTextException e) {
-      String error = e.getMessage();
-      if (error == null || error.isEmpty()) {
-        error = MESSAGES.malformedInputError();
+      if (!inMultiselectMode()) {
+        String error = e.getMessage();
+        if (error == null || error.isEmpty()) {
+          error = MESSAGES.malformedInputError();
+        }
+        Window.alert(error);
       }
-      Window.alert(error);
       updateValue();  // Restore previous property value.
     }
   }