How to check if a document is checked in, in SharePoint Designer Workflow?

I开发者_StackOverflow社区 am trying to create a SharePoint designer workflow which should be triggered every time a document is checked in.

How do I pause till the document is checked in? Will the condition

Wait For "Checked Out To" "To Be Empty" work fine?

Some posts on MSDN and CodePlex indicate that this might throw an error.

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Do you have the possibilty to create (and more importantly, deploy) your own Workflow activities using Visual Studio? I.e. Are you allowed to use custom dll's in your sharepoint farm environment?

If so you could create an activity that uses the following code:

if (SPListItemFromWorkflowListItemProperty.File.CheckOutStatus != SPFile.SPCheckOutStatus.None)
{
  // do your stuff here, like pause the workflow
}