Me.WebTab1.ClientEvents.MouseDown = "WebTab1_MouseDown"
this.WebTab1.ClientEvents.MouseDown = "WebTab1_MouseDown";
// The client event MouseDown takes two parameters sender and e // sender is the object which is raising the event // e is the TabMouseEventArgs function WebTab1_MouseDown(sender, e) { var tab = sender; //Gets the index of the tab involved in the MouseDown event var tabIndex = e.get_tabIndex(); //Gets index of scroll button involved in mouse event. //Possible values: 0 - right or top scroll button, 1 - left or bottom scroll button, // -1 - it is event over tab item or add-new-tab button var scrollButtonIndex = e.get_scrollButtonIndex(); //Assuming you have a label called labelOutput on the form var label = $get('labelOutput'); if (e.isAddNewTabButton()) { label.innerHTML = "Mouse down on add new tab button"; } else if (e.isCloseButton()) { label.innerHTML = "Mouse down on close button with tab index" + tabIndex; } else if (tabIndex != -1) { label.innerHTML = "Mouse down on the tab with index '" + tabIndex + "'"; } else { if (scrollButtonIndex == 0) { label.innerHTML = "Mouse down on the right scroll button"; } else label.innerHTML = "Mouse down on the left scroll button"; } }