### 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> style_minimap_camera = make_flat_stylebox(Color(0.65, 0.65, 0.65, 0.2), 0, 0, 0, 0, 0);
	style_minimap_camera->set_border_color(Color(0.65, 0.65, 0.65, 0.45));
	style_minimap_camera->set_border_width_all(1);
	theme->set_stylebox("camera", "GraphEditMinimap", style_minimap_camera);
	theme->set_stylebox("node", "GraphEditMinimap", make_flat_stylebox(Color(1, 1, 1), 0, 0, 0, 0, 2));
	theme->set_icon("resizer", "GraphEditMinimap", icons["resizer_nw"]);
	theme->set_color("resizer_color", "GraphEditMinimap", Color(1, 1, 1, 0.85));
	
	default_icon = icons["error_icon"];
	
	default_style = make_flat_stylebox(Color(1, 0.365, 0.365), 4, 4, 4, 4, 0, false, 2);
}
void make_default_theme(float p_scale, Ref<Font> p_font, TextServer::SubpixelPositioning p_font_subpixel, TextServer::Hinting p_font_hinting, TextServer::FontAntialiasing p_font_antialiasing, bool p_font_msdf, bool p_font_generate_mipmaps) {
	Ref<Theme> t;
	t.instantiate();
	Ref<StyleBox> default_style;
	Ref<Texture2D> default_icon;
	Ref<Font> default_font;
	Ref<FontVariation> bold_font;
	Ref<FontVariation> bold_italics_font;
	Ref<FontVariation> italics_font;
	float default_scale = CLAMP(p_scale, 0.5, 8.0);
	if (p_font.is_valid()) {
		
		default_font = p_font;
	} else {
		
		
		
		Ref<FontFile> dynamic_font;