GXT: How to add a custom button in the toolbar header

No need to alter tool-sprites.gif, instead I would create an additional image tr-print.png and use the following CSS rules in your custom CSS file:

.x-tool-print{background:transparent url(../images/custom/tr-print.png) no-repeat 0 0;}

.x-tool-print-over{background-position:-1px 0;}

then call:

//Print

panel.getHeader().addTool(new ToolButton("x-tool-print" ,new SelectionListener() {

@Override

public void componentSelected(IconButtonEvent ce) {

final Window w = new Window();

PrintContainer printContainer = new PrintContainer();

printContainer.refresh();

w.add(printContainer);

w.show();

w.maximize();

}

}));