How can I tab away from a Fl_Button in FLTK? - c++

Question

I have a custom class, CustomButton that extends Fl_Button. On my screen there are a bunch of Fl_Input and CustomButton widgets that I want to be able to navigate between using a tab keypress. Tabbing between input fields works fine, but once a CustomButton gets focus, I can't seem to tab away from it.
Here's my handle function
int CustomButton::handle ( int event )
{
int is_event_handled = 0;
switch (event)
{
case FL_KEYBOARD:
// If the keypress was enter, toggle the button on/off
if (Fl::event_key() == FL_Enter || Fl::event_key() == FL_KP_Enter)
{
// Do stuff...
}
is_event_handled = 1;
break;
case FL_FOCUS:
case FL_UNFOCUS:
// The default Fl_Button handling does not allow Focus/Unfocus
// for the button so mark the even as handled to skip the Fl_Button processing
is_event_handled = 1;
break;
default:
is_event_handled = 0;
break;
}
if ( is_event_handled == 1 ) return 1;
return Fl_Round_Button::handle ( event );
}
I am using fltk 1.1.10.

Answer 1

For a very simple, minimal example which demonstrates how to control the focus, please check the navigation.cxx test file.
Maybe your widget did get the focus (check this with Fl::focus()), but it does not show that up (you need to handle the FL_FOCUS and/or FL_UNFOCUS events)?

Answer 2

My problem was my CustomButton::handle() returning 1 after a FL_KEYBOARD event without actually using the tab key press.
Moving is_event_handled = 1 into the if statement lets me consume the FL_Enter keypress only and lets other widgets (i.e. the Fl_Group that controls navigation) take any other keypresses.
Alternatively get rid of the if and replace with something like
switch(Fl::event_key())
{
case FL_Enter:
case FL_KP_Enter:
// Do stuff
is_event_handled = 1;
break;
default:
is_event_handled = 0;
break;
}