Locking a record in GANTT chart that has dependencies

When using the GANTT block is there a way to lock the dates of an individual start and end date of an item? I want to prevent an item that has a predecessor getting automatically moved if I adjust the predecessor in a way that violates the time dependency. I want the line showing the dependency to change to a red dashed line instead to highlight the problem, in the same way as it is highlighted when a dependency is first created is highlighted if the dates of the two items are incompatible.