Question

I’m trying to create my own compound button, using a div as the outer parent:

public class CompoundButton extends ButtonBase {
    public CompoundButton() {
        super(DOM.createDiv());
    }
}

the constructor of ButtonBase wants an Element instance, though, so I’m using that DOM.createDiv() call. But how can I add child widgets now at this point?:

public CompoundButton() {
    super(DOM.createDiv());  <-- we're just a div.

    // ButtonBase has no "add()" method - but this class is really 
    // just a div instance, so shouldn't I be able to convert it to 
    // a FlowPanel for example to be able to add elements to it here?
    this.add(new FlowPanel());   <-- not possible, "add()" not available here.

Thanks

Answer 1

Button base takes a cell, and flowpanel is not a cell and your code for compound button is wrong as it does not sends a cell to its parent.

Proper code is

public class CompoundButton<C> extends ButtonBase<C>
{
   protected CompoundButton( ButtonCellBase<C> cell )
   {
        super( cell );
   }
}