Developer Notes

The old code didn't handle the mouse click (no good), it allowed for this behavior, but also would cause things like clicks passing through buttons and activating stuff in the viewport (no good). So - the SButton no longer returns Unhandled, and returns handled. The correct way to do this now would be to override OnPreviewMouseDown, instead of OnMouseDown - and then have the same code as before.


When using the left mouse button to click and drag a button, the on drag detected will not fire even when using precise click. This was not the case in previous versions of the engine (Works as expected in 4.16, issue appears in 4.17.1)

Regression: Yes

Steps to Reproduce
  1. Download attached project
  2. Open project
  3. Play in editor
  4. Click and drag on the button on screen

Result: The on drag detected does not fire off when using precise click
Expected: When using precise click the button would not consume the mouse input and the on drag detected would fire off when clicking and dragging

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By Design
ComponentTools - UMG
Affects Versions4.17.1
CreatedAug 31, 2017
ResolvedSep 8, 2017
UpdatedJun 23, 2018