update remove button for editors

mindplot/src/main/javascript/libraries/bootstrap/BootstrapDialog.js

@@ -54,7 +54,6 @@ var BootstrapDialog = new Class({
             this.removeButton = $('<button type="button" class="btn btn-secondary" id="removeBtn" data-dismiss="modal">'+ $msg('REMOVE') +'</button>');
             footer.append(this.removeButton);
             this.removeButton.on('click', this.options.onRemoveClickData, this.onRemoveClick);
-            this.removeButton.hide();
         }
         if (this.options.cancelButton) {
             footer.append('<button type="button" class="btn btn-secondary" data-dismiss="modal">'+ $msg('CANCEL') +'</button>');

mindplot/src/main/javascript/widget/LinkEditor.js

@@ -116,6 +116,11 @@ mindplot.widget.LinkEditor = new Class({
 
     onDialogShown: function() {
         $(this).find('#inputUrl').focus();
+    },
+
+    onRemoveClick: function(event) {
+        event.data.model.setValue(null);
+        event.data.dialog.close();
     }
 
 });

mindplot/src/main/javascript/widget/NoteEditor.js

@@ -82,6 +82,11 @@ mindplot.widget.NoteEditor = new Class({
 
     onDialogShown: function() {
         $(this).find('textarea').focus();
+    },
+
+    onRemoveClick: function(event) {
+        event.data.model.setValue(null);
+        event.data.dialog.close();
     }
 });