I just had a need for this, so I followed Animal's advice and added a dblclick listener to the tab. Then I just call a function that collapses all panels so that the editor area is maximized.

PHP Code:
            this.edit = new Ext.TabPanel({
                
region'center'
            
});

            
this.edit.on('render', function(tabpanel){
                
Ext.EventManager.on(tabpanel.getEl(), 'dblclick', function(e){
                    var 
target e.getTarget();
                    var 
ele Ext.get(target);
                    if (
ele.hasClass('x-tab-strip-text')){
                        if (!
this.edit.maximized){
                            
this.collapseAllPanels();
                            
this.edit.maximized true;
                        } else {
                            
this.expandAllPanels();
                            
this.edit.maximized false;
                        }
                    }
                }, 
this);
            }, 
this);