When several users work simultaneously on certain project and then try to check in their project to the DTR, conflicts may occur. A check-in conflict occurs when the version that is being checked in is not a direct successor of the currently active version in the workspace. This can happen in the following cases:
More information: Managing Activities
Merge conflicts can occur when a number of users modify the same composite application simultaneously and if another user has already checked in the same application. To check in the project, the user first needs to resolve the conflict.
You have checked in your project to the DTR. You have modified a composite application that is already under version-control within the Design Time Repository (DTR).
Synchronizing the Project
Open the Composite Application perspective, click your project with the secondary mouse button and choose Team → Sync.
Using The Merge Tool
A three-way merge is displayed. The local version of the project is displayed on the left side of the screen. The conflicting version is on the right side. This is the remote version of the same project.
A conflicting node enclosed in a blue rectangle indicates it can be automatically merged. If it is enclosed by red rectangle, it cannot.
You can restore the original value of the property on the left side. To do this, select a node and choose with the quick info text Reset Conflict.
You have merged the local version of the project with the remote one.