improve GroupView GUI (sensitive buttons)

www/manager/dc/GroupView.js

@@ -22,18 +22,9 @@ Ext.define('PVE.dc.GroupView', {
             store.load();
         };
 
-        var tbar = [
-            {
-		text: 'Create',
-		handler: function() {
-		    var win = Ext.create('PVE.dc.GroupEdit', {
-		    });
-		    win.on('destroy', reload);
-		    win.show();
-		}
-            },
-            {
+  	var remove_btn = new Ext.Button({
 	    text: 'Delete',
+	    disabled: true,
 	    handler: function() {
 		var sm = me.getSelectionModel();
 		var rec = sm.getSelection()[0];
@@ -60,15 +51,31 @@ Ext.define('PVE.dc.GroupView', {
 		    });
 		});
 	    }
+	});
+
+	var tbar = [
+            {
+		text: 'Create',
+		handler: function() {
+		    var win = Ext.create('PVE.dc.GroupEdit', {
+		    });
+		    win.on('destroy', reload);
+		    win.show();
 		}
+            },
+	    remove_btn
         ];
 
+	var set_button_status = function() {
+	    var sm = me.getSelectionModel();
+	    var rec = sm.getSelection()[0];
+	    remove_btn.setDisabled(!rec);
+	};
 
 	Ext.apply(me, {
 	    store: store,
 	    stateful: false,
 	    tbar: tbar,
-
 	    viewConfig: {
 		trackOver: false
 	    },
@@ -87,9 +94,8 @@ Ext.define('PVE.dc.GroupView', {
 		}
 	    ],
 	    listeners: {
-		show: function() {
-		    store.load();
-		}
+		show: reload,
+		selectionchange: set_button_status
 	    }
 	});