How can I update the status messages in Firefox from any thread?

Question

I encountered a problem with updating the status message on Firefox from a Plugin code.

As the documentation says calling NPN_Status works only when called from the main thread. My requirement is to update the status from any thread within the Firefox process.

Any help would be appreciated!

Answer 1

You can't update it from any thread because that would violate some of the threadsafety rules. You will have to proxy your update back to the main thread.

Answer 2

Like sdwilsh said, you are to call the NPN_*-functions only from the main thread. NPN_PluginThreadAsyncCall was only introduced in Gecko 1.9 and isn't supported in all current browsers.

Workarounds depend on the platform:

• on Windows subclass the window your plugin receives, post/send messages to it and invoke the call from the handling window process
• on Mac with Cocoa you can use e.g. performSelectorOnMainThread
• on Mac with Carbon you can use invoke the calls on the null event
• ... etc.