To implement a context-menu you can use a code as showed in the following example:

// set up a command
var com = new qx.client.Command;
com.addEventListener("execute", function(e){
    this.debug("What object i've clicked on?");
    // show the opening widget
    this.debug("e.getData() = " + e.getData().getParentMenu().getOpener());
}, this);
 
// set up the context-menu
var cmenu = new qx.ui.menu.Menu;
// setup the button and add the command
var m_1 = new qx.ui.menu.Button("Show Target", null, com);
cmenu.add(m_1);
cmenu.addToDocument();
 
// show the context-menu
image.setContextMenu(cmenu);
image.addEventListener("contextmenu", function(e) {
            this.getContextMenu().setLeft(e.getClientX());
            this.getContextMenu().setTop(e.getClientY());
 
            // this step is important - set the image as the opening widget
            this.getContextMenu().setOpener(this);
 
            this.getContextMenu().show();
}, image);

The implementation of the context-menu will be rewritten to allow an easier use of this feature. In the new implementation the last section should not be needed. With a correct implementation of the context-menu only the call of

image.setContextMenu(cmenu);

should be needed to setup and use a context-menu.