Why not just make the code in your combo box ActionListener.actionPerformed method available to the other part of the program? For example make it a method in a class that both parts of the program can access, or pass the action code to the other part of the program, for example, something like this:
// create an Action to refresh the editor
Action refreshEditorAction = new AbstractAction("Refresh Editor") {
public void actionPerformed(ActionEvent e) {
... // refresh editor
}
}
...
// elsewhere add the action to the combo box
comboBox.addActionListener(refreshEditorAction);
...
// elsewhere again - method to update the display
void updateDisplay(String newContent, Action refreshEditor) {
updateEditorContent(newContent);
refreshEditor.actionPerformed(null);
}
...
// elsewhere - calling the updateDisplay method
String newEditorContent = getNewEditorContent();
updateDisplay(newEditorContent, refreshEditorAction);
...