### 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
hue_gradient->set_colors(colors);
		Ref<GradientTexture2D> hue_texture;
		hue_texture.instantiate();
		hue_texture->set_width(800);
		hue_texture->set_height(6);
		hue_texture->set_gradient(hue_gradient);
		theme->set_icon("color_okhsl_hue", "ColorPicker", hue_texture);
	}
	
	theme->set_icon("bg", "ColorPickerButton", icons["mini_checkerboard"]);
	theme->set_stylebox("normal", "ColorPickerButton", button_normal);
	theme->set_stylebox("pressed", "ColorPickerButton", button_pressed);
	theme->set_stylebox("hover", "ColorPickerButton", button_hover);
	theme->set_stylebox("disabled", "ColorPickerButton", button_disabled);
	theme->set_stylebox("focus", "ColorPickerButton", focus);
	theme->set_font("font", "ColorPickerButton", Ref<Font>());
	theme->set_font_size("font_size", "ColorPickerButton", -1);
	theme->set_color("font_color", "ColorPickerButton", Color(1, 1, 1, 1));
	theme->set_color("font_pressed_color", "ColorPickerButton", Color(0.8, 0.8, 0.8, 1));
	theme->set_color("font_hover_color", "ColorPickerButton", Color(1, 1, 1, 1));
	theme->set_color("font_focus_color", "ColorPickerButton", Color(1, 1, 1, 1));
	theme->set_color("font_disabled_color", "ColorPickerButton", Color(0.9, 0.9, 0.9, 0.3));
	theme->set_color("font_outline_color", "ColorPickerButton", Color(1, 1, 1));
	theme->set_constant("h_separation", "ColorPickerButton", 2 * scale);
	theme->set_constant("outline_size", "ColorPickerButton", 0);
	
	Ref<StyleBoxFlat> preset_sb = make_flat_stylebox(Color(1, 1, 1), 2, 2, 2, 2);
	preset_sb->set_corner_radius_all(2);
	preset_sb->set_corner_detail(2);
	preset_sb->set_anti_aliased(false);