As part our case processing on the UI screen we have configured navigation menu which holds different values like Refresh,History and attachments, Write email, Pulse, Where Am I etc. So for Write email navigation menu option  we configured some action set like running some "SendEmail" flow in  OOTB FLOW IN MODAL DIALOG action So when ever clicks on write email option then modal dialog will be getting opened which contains two buttons like Cancel and Send Email (customized from existing OOTB Submit button) Now when user clicks on Send email , the send email flow is getting successfully completed and user could able to successful proceed further in case processing in pega on click of next. Suppose if user selects Cancel button , modal dialog is getting closed but  when user trying to proceed further in case processing he could not able to succesfully proceed further in case processing in pega on click of pega. Note: Flow in modal dialog option usage is creating and running on new thread in clipboard ,now unless and until entire "SendEmail" flow completes its execution the page is not getting merged in parent page. Below is the link which contains how flow in modal dialog works:

https://docs-previous.pega.com/user-experience-theme-ui-kit/86/available-actions-and-conditions Outcome we are expecting right now is :

When user clicks on Cancel button of flow in modal dialog , he should successfully able to proceed further in case processing