GTKD - CSS class color "flash" delay

[TheDGuy via Digitalmars-d-learn]

On Saturday, 25 June 2016 at 13:01:09 UTC, TheDGuy wrote:
> Thanks for your answer.
> I have to pass the Button object to my timeout function to 
> change the CSS class. But how do i do that within the Timeout 
> constructor?

I mean:

I have to pass my function and delay time to the constructor, but 
i can't pass any data to the function here, also only functions 
are allowed (at least it looks like that to me) who don't have 
parameters.

If i want to add a new function i have to use the function 
.add(), with this function i can pass 'userData' (so my button 
for example). But why am i unable to do that in the constructor? 
Do i have 2 different functions for the same thing, one with the 
other one without parameter?

My current approach:

     private void letButtonsFlash(){
         foreach(Button btn;bArr){
             btn.setSensitive(false);
         }
         for(int i = 0; i < level; i++){
             Button currentButton = bArr[rndButtonBlink[i]];
             ListG list = 
currentButton.getStyleContext().listClasses();
             string CSSClassName = 
to!string(cast(char*)list.next().data);
             currentButton.getStyleContext().addClass(CSSClassName 
~ "-flash");
             //writeln(CSSClassName);
             Timeout t = new Timeout(&timeout_delay,5,false); 
//error appears here
             t.add(5,&timeout_delay,currentButton);
         }
         foreach(Button btn;bArr){
             btn.setSensitive(true);
         }
     }
     bool timeout_delay(Button currentButton){
         ListG list = 
currentButton.getStyleContext().listClasses();
         string CSSClassName = 
to!string(cast(char*)list.next().data);
         currentButton.getStyleContext().removeClass(CSSClassName 
~ "-flash");
         return false;
     }

But i get the error:
Error: none of the overloads of '__ctor' are callable using 
argument types (bool delegate(void* userData), int, bool), 
candidates are:
glib.Timeout.Timeout.this(uint interval, bool delegate() dlg, 
bool fireNow = false)
glib.Timeout.Timeout.this(uint interval, bool delegate() dlg, 
GPriority priority, bool fireNow = false)
glib.Timeout.Timeout.this(bool delegate() dlg, uint seconds, bool 
fireNow = false)
glib.Timeout.Timeout.this(bool delegate() dlg, uint seconds, 
GPriority priority, bool fireNow = false)

If i take a look at GTK for C it looks like there is a function 
for that:

http://www.gtk.org/tutorial1.2/gtk_tut-17.html

Why is this so confusing?