Hi Stefan

For the sake of the following discussion I will assume that you are using the latest version of G4P i.e. V1.6.3 and that you have created a GWindow object called win

The normal window Exit also seems to be disabled

This is the default behaviour of GWindow objects but you can change that with
win.setActionOnClose( flag );

where flag can have one of three values
GWindow.KEEP_OPEN - ignore attempt to close window (default action)
GWindow.CLOSE_WINDOW - close this window, if it is the main window it causes the app to exit
GWindow.EXIT_APP - exit the app, this will cause all windows to close.

If you want to close a GWindow without using the Window Exit button, for instance you might use a GButton in one window to close another window then it is more difficult. The reason being that when I created the library I did not think to include this feature.

The good news is that it will be in the next version of G4P, the other good news is that the function can be done using the method below. Simple copy the code below into your sketch and to close our GWindow use

closeWindow(win);

1. void closeWindow(GWindow window) {
2.   PApplet a = window.papplet;
3.   a.noLoop();
4.   try {
5.     a.unregisterPost(a);
6.   }
7.   catch(Exception excp) {
8.   }
9.   try {
10.     a.unregisterDraw(a);
11.   }
12.   catch(Exception excp) {
13.   }
14.   try {
15.     a.unregisterPre(a);
16.   }
17.   catch(Exception excp) {
18.   }
19.   try {
20.     a.unregisterMouseEvent(a);
21.   }
22.   catch(Exception excp) {
23.   }
24.   G4P.removeWindow(window);
25.   window.dispose();
26. }

Unfortunately G4P does not support menu creation, although you could simulate a menu using some GCombo components.

First the P2D and P3D text display problem.

To fix this problem add the following line to the setup() method after the size() statement
G4P.setTextMode(SCREEN);

I know this will fix the main screen but if it doesn't fix the secondary windows (ie the GWindows objects) let me know.

To handle GButton events you MUST have the following method to handle them, this should handle events from all buttons even if they are in another window

void handleButtonEvents(GButton button) {
      // Handle events from ALL GButton events
      // add this line to see which button was clicked
      println(button.getText();
}

If you want a separate event handler for a GButton then create your own method using the signature provided by the warning eg

void handleOtherButtonEvents(GButton button) {
      // add this line to check which button was clicked
      println(button.getText();
}

Now if you have two GButtons called btnDoesOne and btnDoesTwo then use the next lines to add this event handler to the buttons

btnDoesOne.addEventHandler(this, "handleOtherButtonEvents");
btnDoesTwo.addEventHandler(this, "handleOtherButtonEvents"); 

You can see it is possible for all components to have their own event handlers or share them, the choice is yours.

You can do the same for the GOption component but the handler method signature has 2 GOption parameters the first for the option being selected and the second for the option that was deselected.

As to the warnings - they are just that warnings and can be ignored. For instance the GPanel component generates an event when it is collapsed or expanded but you may not want to do anything so the warning can be safely ignored and you don't have to provide a handler.

Warnings can also be disabled with the following statement in setup() but only do this when you are happy with the program.

G4P.messagesEnabled(false);

It a great library you've created. I get a bit lost when looking at the reference stuff. No reflection on your efforts more my lack of understanding.

Thanks for the praise I am glad you like the library. I always think that the documentation should be written by someone other than the programmer. The problem with the programmer is that they know too much about the workings of the code so tend to write very sparse or very technical explanations which are of little use to the library user. I have tried to avoid that but I am not always successful

Hope this helps

Don't use G4P.setTextMode(SCREEN); with JAVA2D or OPENGL.

Unless you are drawing in 3D there seems little point in using P3D and in your application I can't see any benefit to using P2D so stick to Java2D.

From
second_port.handleButtonEvents(button);

It appears that you want an object of another class to handle the event handling.

If you want this object ( second_port) to handle the events for a GButton called btnDoesOne then use

btnDoesOne.addEventHandler(second_port, "handleButtonEvents");

and make sure you have created the method in the class that defines second_port
 and that second_port has been created