Looks like we can't reproduce the issue or there's a problem in the test case provided.
Sencha Premium Member
am following your help guide on the designer (build 288) and touch (both beta versions) and have come to the part on adding a combo....where is it?
Can't find it in any of the tools sections of the toolbox?
Type "Combo" into the toolbox filter and it will show the combobox component when using the Ext 4.x framework.
Type "Select" into the toolbox filter for Sencha Touch and it will show the select field.
Should be under Forms and Views category as well