Etwas

            items:[{
                xtype:"form",
                name:"Operationen",
                buttons:[{
                    text:"Speichern"
                  },{
                    text:"Abbrechen"
                  }],
                title:"Daten bearbeiten",
                autoHeight:true,
                items:[{
                    xtype:"combo",
                    fieldLabel:"Patient",
                    name:"Patient"
                  },{
                    xtype:"datefield",
                    fieldLabel:"OP-Datum",
                    name:"OP-Datum"
                  },{
                    xtype:"combo",
                    name:"Operateur",
                    fieldLabel:"Operateur"
                  },{
                    xtype:"fieldset",
                    title:"Diagnosen-Details",
                    layout:"form",
                    items:[{
                        xtype:"combo",
                        fieldLabel:"Kategorie"
                      },{
                        xtype:"combo",
                        fieldLabel:"Subkategorie"
                      }]
                  }]
              }]