The place to report Pale Moon specific bugs on the Windows operating system.
Is the inBackground parameter of the gBrowser.loadOneTab function still supposed to be respected? I'm testing an extension of mine that makes use of the parameter in Pale Moon and Basilisk, and with the "When I open a link in a new tab, switch to it immediately" preference enabled, the tab that's supposed to be loaded in the background is instead loaded in the foreground, resulting in all kinds of unwanted behavior and non-functionality. Does it rely on any other parameters or methods of being called to function correctly? I've tried both the single array parameter and independent parameters with the same result.
I use it in my extension and everything works as expected regardless of the "browser.tabs.loadInBackground" setting.
Here are the add-ons I made in a spare time. That was fun!
Does your extension try to grab the selected text of the current tab immediately after trying to load a new tab in the background?