multithreading - Onchanged c# appending form -

i trying append textbox everytime there change in log text file in c#.

below code cant seem it. keep tells me access textbox component in main form thread c#

public form1() {      initializecomponent();      string currentpath = system.environment.currentdirectory;       filesystemwatcher watcher = new filesystemwatcher();     watcher.path = currentpath;     watcher.notifyfilter = notifyfilters.lastaccess | notifyfilters.lastwrite                            | notifyfilters.filename | notifyfilters.directoryname;     watcher.filter = "*.*";     watcher.changed += new filesystemeventhandler(onchanged);     watcher.enableraisingevents = true;       }  private void onchanged(object source, filesystemeventargs e) {     textbox1.appendtext("hello ah"); } 

filesystemwatcher delivers events on different thread, have marshall appendtext calls ui dispatcher:

textbox1.dispatcher.begininvoke(new action(() =>       {           textbox1.appendtext("hello ah");       }));