in (FileMaker Pro 12)
If you move a tab control and the fields do not move with it, the fields have not been successfully placed into a panel of the tab control such that the tab panel "owns" the objects. This can happen especially if you place the objects on the layout and then use the Inspector's alignment tools to pull the items into position so that it looks like they are part of the tab control but actually they are floating above it.
step 1. Make sure that no part of the tab control touches or crosses the boundary between layout parts such as the line separating the header and body parts.
step 2. drag the object away from the tab panel and release the mouse button.
step 3. drag the object back and do not release the mouse button until all edges of the object are fully inside the boundaries of the tab panel.
step 4. drag the tab control a few pixels to make sure that the object moves when you move the tab control
Step 5. If necessary, you can now use the alignment tools and other controls in the inspector to fine tune the object's position within the tab panel.