I'm making a paint programme, for some reason, and I wanted it to query whether the user wanted to save before they left if they had made changes. Now to save it uses the same code as when I press CTRL+S, but for some reason when it's closing (and only when you press the X in the top right hand corner to do this, as if I press ESC in my programme it runs it perfectly well). These are the two functions, shutdown and save. Shutdown:

void shutdown(){
if (changes){
int todo = MessageBox(win_get_window(), "Do you want to save changes before you leave?", "Save", MB_YESNOCANCEL | MB_ICONQUESTION | MB_DEFBUTTON1);
if (todo == IDNO) run = 0;
if (todo == IDYES) { save(); run = 0;}
}
else
run =0;
}

Run is the boolean which the entire programmed is encased it. IE while (run) {//game} Changes is just a boolean that contains if the user has made any changes. This seems to work fine, the place that it freezes at is in the save function. Which if I call in two other ways, works: save()

void save(){
   char path[480];
   sprintf(path, "./");
   int ok = file_select_ex("Save", path, "bmp", 480, 300, 300);
   if (ok){
   save_bitmap(path, image, NULL);
   changes = 0;
   }
}

It freezes at the line file_select_ex(), which is an allegro function, and it's blocking. Now I gueses that when you click the X it doesn't like blocking functions, which is screwed, so how can I fix this (I was going to change to the Win32 one soon anyway).

It sounds like file_select_ex is dependent on the parent window being valid. Since the 'x' button was clicked, the window was probably destroyed. You might want to see if there is a way to intercept the window close request and do your save there, before the window is actually closed.