How do I use Touch to drag & drop an item from inside a TileView ?

Development Programming & Scripting
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Hello everyone.
I have a problem using UMG, in C++ and in Blueprint, be it on my current project or a new fresh one. I have spent weeks searching forums & the internet and trying stuff on my own, to no avail. It is a seemingly trivial problem that I cannot figure out and it’s driving me insane.

Problem: Drag & Drop of items (Widgets) within a Widget with scroll capability (here, TileView) does not work. The touch is automatically used by the TileView to enable scroll. OnTouchStarted() is not even called on the Item. Drag & Drop of items works when placing the items in a widget that cannot scroll.

Tried solutions: (in no particular order)

  • Enable Use Mouse as touch in Editor Preferences.
  • Enable Use Mouse as touch in Project Settings.
  • Enable touch events in the PlayerController.
  • Enable touch over events in the PlayerController.
  • Set ConsumeMouseWheel on the TileView to False (touch scroll keeps working).
  • Set WheelScrollMultiplier on the TileView to 0 (touch scroll keeps working).
  • Set the TileView to IsFocusable = true and its items to IsFocusable = true.
  • Set the TileView to IsFocusable = true and its items to IsFocusable = false.
  • Set the TileView to IsFocusable = false and its items to IsFocusable = false.
  • Set the TileView to IsFocusable = false and its items to IsFocusable = true.
  • Set the Priority of the Items to 99.
  • Enable the StopAction of the Items.
  • Tried to override OnTouchStarted() on the TileView, cannot find it.
  • Disable the StopAction of the Items.
  • Enable the Return Focus to Selection on the TileView.
  • Disable the Return Focus to Selection on the TileView.
  • Set the InputMode to InputModeGameAndUi(), InputModeUiOnly(), and InputModeGameOnly().
  • Enable Allow Dragging on the TileView.
  • Try all combinations of Visibility on the TileView and its Items.
  • Transform the Items into Buttons to take advantage of their OnPressed() which is always called when touched.
  • Reproduce the problem on an empty project to confirm that the problem comes from Unreal and not from a bug in the project.
  • Use the fact that the LongPress of OnTouchGesture is triggered to create an identical widget on top of the TileView that would solely serve to detect the drag & drop event → OnTouchStarted() is not triggered as soon as the widget appears. I have to release and touch it again to finally begin drag, which is not ideal at all.

I don’t have any more idea on what to do. Any help would be greatly appreciated.

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Anyone ?

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If you make tileview with buttons, changing button’s click method and touch method might help you changing click method to ( Down and Up → Precise Click) and touch mehtod to (Down to Up → Precise Tap)