I have a button in salesforce when clicked opens a visualforce page. And when the button is clicked twice it opens two windows of visualforce pages. I want the window to be opened only once. If the window is already open, i need to show an alert popup like 'window is already open' and may be focus it. So is there any way to check if the visualforce page is already open.
The button is present on another page too which opens the same visualforce page. So disabling the button on first click will work only for the button on same page