Every Ext widget can be pretty much styled to your liking using CSS. The default Ext CSS for button image has expects a 16x16 image. But you can change the style to size the button to display your 32x32 image.
Button iconButton = new Button();
iconButton.setIcon("images/save.png");
iconButton.setCls("mybutton-text-icon");
iconButton.setTooltip("My Button");
from the ext forum :
/* remove the default left,center and right images from the button border*/
.mybutton-text-icon .x-btn-left, .mybutton-text-icon .x-btn-right, .mybutton-text-icon .x-btn-center {
background: 0;
}
/* now customize the new button that has a caption below the icon */
.mybutton-text-icon .x-btn-center .x-btn-text {
background-position: 0 2px;
background-repeat: no-repeat;
padding-left: 0px;
padding-top: 32px;
padding-bottom: 0px;
padding-right: 0px;
height: 32px;
width: 32px;
}
I'm hoping to capture CSS info for customizing the widgets in the Javadocs, but in the mean time you can post your question, search the Ext forums, or better yet use Firebug to examine the CSS being applied, dynamically alter them till you get the desired result and then capture those rules in your CSS file.
I'll add the above info to the Button Javadocs.
Sanjiv