Firefox extension, opening a local file in a new foreground tab from menu - firefox

Question

I am learning how to program Firefox extensions. I have created a new menu and when the menu item is clicked, I want a new tab to be opened, in the foreground, containing a local file contained within the contents directory.
For example:
MENU -> Item1
When Item1 is selected, I want a new tab to open in the foreground containing what is located in /myextension/content/content.html.
Where can I find out how to do this?
For clarity, I can get the local file to open in a new tab, I just do not know how to get to open in a new focused tab.

Answer 1

I use the following function to open a tab, make sure it hasn't already been opened and switch focus to it:
function OpenAndReuseOneTabPerURL(url)
{
var wm = Components.classes["#mozilla.org/appshell/window-mediator;1"].getService(Components.interfaces.nsIWindowMediator);
var browserEnumerator = wm.getEnumerator("navigator:browser");
// Check each browser instance for our URL
var found = false;
while (!found && browserEnumerator.hasMoreElements())
{
var browserWin = browserEnumerator.getNext();
var tabbrowser = browserWin.gBrowser;
// Check each tab of this browser instance
var numTabs = tabbrowser.browsers.length;
for (var index = 0; index < numTabs; index++)
{
var currentBrowser = tabbrowser.getBrowserAtIndex(index);
if (url == currentBrowser.currentURI.spec)
{
// The URL is already opened. Select this tab.
tabbrowser.selectedTab = tabbrowser.tabContainer.childNodes[index];
// Focus *this* browser-window
browserWin.focus();
found = true;
break;
}
}
}
// Our URL isn't open. Open it now.
if (!found)
{
var recentWindow = wm.getMostRecentWindow("navigator:browser");
if (recentWindow) {
// Use an existing browser window
recentWindow.delayedOpenTab(url, null, null, null, null);
} else {
// No browser windows are open, so open a new one.
window.open(url);
}
}
}
Use it like:
OpenAndReuseOneTabPerURL("http://yoururl.com");