When using mutliple monitors connected to a Mac the mouse behavior does not function well. Attempting to navigate and drag windows to and from individual displays proves difficult.

The user reporting the issue as well as another user managed to narrow it down to physical position of the Mac screen and the external monitors.

"After some experimentation I've traced the issue back to the screen layout/arrangement, (2 & 3 are the 23" DELL DVI monitors and 1 is the macbook itself.)
With the main macbook internal monitor logically below the other two in the arrangement (mirrors my desk arrangement) I have the problem of not being able to drag/move objects in the viewport, I can drag tabs around just fine, just not actors/objects as described previously.

However if I change the monitor arrangement to:
Everything works just fine"

Steps to Reproduce

1. Connect an external monitor to a Mac Laptop and adjust its position so that they match the configuration pictured in OffsetScreens.png
2. Create a new blank project with starter content
3. Drag the editor window so that it is on the external monitor.
4. Drag a point light into the viewport and release mouse button to place
5. Select the newly placed point light and attempt to move using the translate widget

Expected: The point light will be able to translate using the translation widget.
Actual: The point light can not be translated on any axis.( attempting to move along the Y axis causes jittering, but no translation)

This behavior only occurs when the window containing the object that you are attempting to move is on the external monitor. dragging the editor to the laptop monitor returns all functionality.

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ComponentUE - Platform - Mac
Affects Versions4.
Target Fix4.8
Fix Commit2547204
Release Commit2547212
CreatedApr 24, 2015
ResolvedMay 12, 2015
UpdatedApr 27, 2018