4.7 RC 1 Can no longer drag and drop .tscn files from the filesystem into the scene dock

[Narik-tech]

Tested versions

Reproducible in 4.7 RC 1
Not reproducible in 4.7 beta 5
Not reproducible in 4.5.1

System information

Windows 11, Godot 4.7 RC 1

Issue description

20260609-0114-10.8322394.mp4

Steps to reproduce

Drag any .tscn file from the FileSystem into a scene dock.

Minimal reproduction project (MRP)

N/A

[saierXP]

All the actions of dragging and dropping files into the scene tree are invalid.
The issue disappeared after reverting #119336.

[Nintorch]

CC @vaner-org

[bruvzg]

The issue seems to be !drop_mode_flags in the Tree::get_drop_section_at_position, it's checking flags of the drop target, and scene tree only set flags after calling get_drop_section_at_position so it's always zero. So it's probably an issue with SceneTreeEditor not a base tree.

[vaner-org]

Thank you for catching this @bruvzg.