Fix right-click on tilset atlas popup wrong position

[groud]

Fixes #71327

[Sauermann]

Technically you are adding points of different coordinate systems:

• get_screen_position() is in Screen/Viewport coordinates
• get_local_mouse_position() is in CanvasItem-local coordinates

I didn't look in depth into this, but could you test, if the PR works, if the editor has a non-default Display Scale and is not in Single-Window-Mode? If not, you could try instead of the addition:
get_screen_transform().xform(get_local_mouse_position())

Conceptually the conversion to the Screen coordinates was definitively missing.

Maybe you could extend this PR to address

godot/editor/plugins/tiles/tile_set_atlas_source_editor.cpp

Line 1976 in e514e37

alternative_tile_popup_menu->popup(Rect2i(get_global_mouse_position(), Size2i()));

[groud]

get_screen_transform().xform(get_local_mouse_position())

This seems indeed cleaner. I'll test it.
And yeah, I need to fix the issue in the other place, you are right. I'll amend the PR.

[groud]

Done. I also fixed a similar issue in AnimationLibraryEditor.

[akien-mga]

Thanks!

[akien-mga]

For the record, there's a few more cases of this get_screen_position() + get_local_mouse_position() which could be worth reviewing:

$ rg get_screen_pos.*get_local_mouse
scene/gui/line_edit.cpp
251:                    menu->set_position(get_screen_position() + get_local_mouse_position());

doc/classes/Control.xml
427:                            popup_menu.position = get_screen_position() + get_local_mouse_position()

editor/editor_audio_buses.cpp
759:    delete_effect_popup->set_position(get_screen_position() + get_local_mouse_position());

editor/plugins/visual_shader_editor_plugin.cpp
3821:                   Point2 gpos = get_screen_position() + get_local_mouse_position();
3840:           Point2 gpos = get_screen_position() + get_local_mouse_position();
4682:                   _comment_title_popup_show(get_screen_position() + get_local_mouse_position(), selected_comment);
4685:                   _comment_desc_popup_show(get_screen_position() + get_local_mouse_position(), selected_comment);

editor/plugins/animation_blend_tree_editor_plugin.cpp
390:    add_node->get_popup()->set_position(graph->get_screen_position() + graph->get_local_mouse_position());

editor/plugins/script_editor_plugin.cpp
3086:   context_menu->set_position(get_screen_position() + get_local_mouse_position());

editor/animation_track_editor.cpp
2821:                           menu->set_position(get_screen_position() + get_local_mouse_position());

editor/editor_inspector.cpp
709:            menu->set_position(get_screen_position() + get_local_mouse_position());

editor/scene_tree_dock.cpp
2604:                   menu_properties->set_position(get_screen_position() + get_local_mouse_position());
2972:           filter_quick_menu->set_position(get_screen_position() + get_local_mouse_position());

editor/debugger/editor_debugger_tree.cpp
120:    item_menu->set_position(get_screen_position() + get_local_mouse_position());

[Sauermann]

From a quick look, there are several occurrences of get_screen_position which look problematic in "scene/gui". I should probably investigate them after my get_screen_transform-fix gets merged.