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);  ```