SMenuAnchor - Assertion failed: NewMenu->GetOwnedWindow().IsValid()

Keagan_sdw
Thu, 30 Mar 2017 00:18:53 +0000
UI

Our project has recently seen a crash with SComboBox using UE 4.14.0. The dropdown menu will flicker constantly when first opened and attempting to click on it can cause a crash.

I’ve been able to repro this in the Slate Viewer app created from the GitHub 4.15.1-release using the following steps:

Open the Slate Viewer application.

Select the Widget Gallery tab.

Position the main window such that the dropdown menu will go beyond the bottom of the screen.

Open the “Item A N” dropdown menu.

Attempt to click on “Item A 1 or 2” in the dropdown making sure that the mouse click is above the Combo Button widget.

### menu Position

### click Area

When the menu opens on top of another ComboButton/Box, the click goes through to the underlying ComboButton/Box and causes the check in SMenuAnchor::SetIsOpen line 379 to fire. This only seems to happen when the newly opened dropdown menu is flickering above and below the original box. If it does not crash, the process must be started over completely as subsequent clicks on the “Item A N” combobox will cause the dropdown to open above the original menu.

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