Safari 5 Extension: How can I detect when a window's current tab has changed?

Question

I have a Safari 5 extension that contains a toolbar. Whenever the current tab changes, that toolbar should be updated. I would like to do something like this from my bar\'s

Answer 1

I found this method works better than focus event, it can be managed in the background page:

safari.application.addEventListener("validate", PopUp.validateCommand, false);

var PopUp = {

    activeTab : null,

    // commands are validated before being excecuted
    validateCommand : function(aEvent) {

        // this is a hack for detecting tab switches, safari does not have a dedicated API like Chrome 
        if(PopUp.activeTab !== null){
            if(PopUp.activeTab !== safari.application.activeBrowserWindow.activeTab){
                $.each(safari.application.browserWindows, function(aIndex, aWindow) {
                    $.each(aWindow.tabs, function(aIndex, aTab) {
                        //  message all tabs about the focus switch event
                        if (aTab !== safari.application.activeBrowserWindow.activeTab && aTab.page) {
                            aTab.page.dispatchMessage("tabUnfocused");
                        }else{
                            aTab.page.dispatchMessage("tabFocused");
                        }
                    });
                });
            }
        }
        // set the new active tab
        PopUp.activeTab = safari.application.activeBrowserWindow.activeTab;
    }
}