Everytime I open a new window to browse, in this new window I would right click to open link in new tab but the new tab always shows up in the other window.

Firefox did have a behavior where some new windows -- those considered to be dialogs -- could not have new tabs, so new tabs were diverted to the window from which the dialog was opened. According to the bug tracking system, a fix is in the works: [https://bugzilla.mozilla.org/show_bug.cgi?id=644729 644729 – Popup window with all toolbars visible causes new tabs to open in another browser window] referencing [https://bugzilla.mozilla.org/show_bug.cgi?id=485237 485237 – Need to treat popups consistently]. That second ones says Target Milestone: Firefox 12, so the fix probably didn't make it into Firefox 11. WORKAROUNDS That first bug says there is an add-on to work around this -- it enables the middle mouse button to open links in a dialog window: [https://addons.mozilla.org/en-US/firefox/addon/bug-586234-unfixer/ Bug 586234 Unfixer :: Add-ons for Firefox]. I haven't tried it myself. Old forum thread cross-reference: [https://support.mozilla.org/en-US/questions/824649 When I open a new tab it opens in the wrong window | Firefox Support Forum | Firefox Help]