When previewing a form in Composer , there is a "Style" dropdown to be able to preview a form in either "Classic" style or "Work Center" style. However, when you open the preview, you may not have "Work Center" available in the dropdown (only Classic is available).
When using Client Cert with Composer if you click OK in composer options on any screen but the Repository tab you lose the selected client certificate.
Web Page Widget added to a View form in Composer will load automatically any time the View form is loaded, despite unchecking all options under the “Refresh:” properties in the widget properties.
If you are using Composer and are connected to the On Demand version of SBM then you aren't allowed to use Appscripts for security reasons. If you are using an On Premise version of SBM but still don't see the Appscript section then open the "Composer Options" in Composer and on the General tab make sure you you don't have the "On Demand" mode set in the Behavior section.