### Godot version

v4.2.dev.custom_build [0c2144da9]

### System information

Debian Linux X11 Xfce

### Issue description

Prerequisite: Be in Single Window Mode in the Editor
The Filesystem Dock is unusable when it is floating, which is not expected.
It appears garbled in the top-left corner:
![image](https://github.com/godotengine/godot/assets/6299227/109f7922-97de-44c3-814a-ca7f970e0602)

The following errors are shown:
```
  editor/window_wrapper.cpp:220 - Condition "!is_window_available()" is true.
  editor/window_wrapper.cpp:202 - Condition "!get_window_enabled()" is true. Returning: Rect2i()
  editor/window_wrapper.cpp:207 - Condition "!get_window_enabled()" is true. Returning: -1
  editor/window_wrapper.cpp:207 - Condition "!get_window_enabled()" is true. Returning: -1
```

bisecting lead to #62378
possibly related to #44439

### Steps to reproduce

1. Start a project in the Editor
2. Switch to Single Window Mode in the Editor and reload (if necessary)
3. Make the Filesystem Dock floating

### Minimal reproduction project

Editor issue
p_config_file->set_value(EDITOR_NODE_CONFIG_SECTION, "selected_main_editor_idx", Variant());
	}
}
void EditorNode::_load_central_editor_layout_from_config(Ref<ConfigFile> p_config_file) {
	
	bool has_active_tab = false;
	if (p_config_file->has_section_key(EDITOR_NODE_CONFIG_SECTION, "selected_bottom_panel_item")) {
		int selected_bottom_panel_item_idx = p_config_file->get_value(EDITOR_NODE_CONFIG_SECTION, "selected_bottom_panel_item");
		if (selected_bottom_panel_item_idx >= 0 && selected_bottom_panel_item_idx < bottom_panel_items.size()) {
			
			if (bottom_panel_items[selected_bottom_panel_item_idx].button->is_visible()) {
				_bottom_panel_switch(true, selected_bottom_panel_item_idx);
				has_active_tab = true;
			}
		}
	}
	if (p_config_file->has_section_key(EDITOR_NODE_CONFIG_SECTION, "center_split_offset")) {
		int center_split_offset = p_config_file->get_value(EDITOR_NODE_CONFIG_SECTION, "center_split_offset");
		center_split->set_split_offset(center_split_offset);
		
		if (!has_active_tab) {
			bottom_panel_items[0].control->show(); 
			_bottom_panel_switch(false, 0);
		}
	}
	
	if (p_config_file->has_section_key(EDITOR_NODE_CONFIG_SECTION, "selected_default_debugger_tab_idx")) {
		int selected_default_debugger_tab_idx = p_config_file->get_value(EDITOR_NODE_CONFIG_SECTION, "selected_default_debugger_tab_idx");
		EditorDebuggerNode::get_singleton()->get_default_debugger()->switch_to_debugger(selected_default_debugger_tab_idx);
	}