### Godot version

4.x (beta 5, 6, 7, 8, 9, 10) didn't tested versions before beta 5
Also reproducable in current master: c5bfe13
  
### System information

Windows 10

### Issue description

When clicking around the bottom edge of the scrollbar grabber, it is not detected as such and instead jumps to a lower position, as if you click on the free area of the scrollbar.

The red marked area is not detected as grabber click. Everything is fine on the top edge.
![image](https://user-images.githubusercontent.com/66004280/210325316-6718b793-b3ec-4c3a-b2b3-0df0f431a222.png)

### Steps to reproduce

Just use a `ScrollContainer` with e.g. a `VBox` and many `Button`s.

See the video:

https://user-images.githubusercontent.com/66004280/210325006-718e0f57-49b3-4aa1-ad35-653b9c66d9fa.mp4

### Minimal reproduction project

N/A
Ref<StyleBoxFlat> graphnode_comment_normal = make_flat_stylebox(style_pressed_color, 18, 42, 18, 12, 3, true, 2);
	graphnode_comment_normal->set_border_color(style_pressed_color);
	Ref<StyleBoxFlat> graphnode_comment_selected = graphnode_comment_normal->duplicate();
	graphnode_comment_selected->set_border_color(style_hover_color);
	Ref<StyleBoxFlat> graphnode_breakpoint = make_flat_stylebox(style_pressed_color, 18, 42, 18, 12, 6, true, 4);
	graphnode_breakpoint->set_border_color(Color(0.9, 0.29, 0.3));
	Ref<StyleBoxFlat> graphnode_position = make_flat_stylebox(style_pressed_color, 18, 42, 18, 12, 6, true, 4);
	graphnode_position->set_border_color(Color(0.98, 0.89, 0.27));
	Ref<StyleBoxEmpty> graphnode_slot = make_empty_stylebox(0, 0, 0, 0);
	theme->set_stylebox("frame", "GraphNode", graphnode_normal);
	theme->set_stylebox("selected_frame", "GraphNode", graphnode_selected);
	theme->set_stylebox("comment", "GraphNode", graphnode_comment_normal);
	theme->set_stylebox("comment_focus", "GraphNode", graphnode_comment_selected);
	theme->set_stylebox("breakpoint", "GraphNode", graphnode_breakpoint);
	theme->set_stylebox("position", "GraphNode", graphnode_position);
	theme->set_stylebox("slot", "GraphNode", graphnode_slot);
	theme->set_icon("port", "GraphNode", icons["graph_port"]);
	theme->set_icon("close", "GraphNode", icons["close"]);
	theme->set_icon("resizer", "GraphNode", icons["resizer_se"]);
	theme->set_font("title_font", "GraphNode", Ref<Font>());
	theme->set_color("title_color", "GraphNode", control_font_color);
	theme->set_color("close_color", "GraphNode", control_font_color);
	theme->set_color("resizer_color", "GraphNode", control_font_color);
	theme->set_constant("separation", "GraphNode", 2 * scale);
	theme->set_constant("title_offset", "GraphNode", 26 * scale);
	theme->set_constant("title_h_offset", "GraphNode", 0);
	theme->set_constant("close_offset", "GraphNode", 22 * scale);
	theme->set_constant("close_h_offset", "GraphNode", 22 * scale);
	theme->set_constant("port_offset", "GraphNode", 0);