### 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
theme->set_stylebox("grabber_pressed", "VScrollBar", style_scrollbar_grabber_pressed);
	theme->set_icon("increment", "VScrollBar", empty_icon);
	theme->set_icon("increment_highlight", "VScrollBar", empty_icon);
	theme->set_icon("increment_pressed", "VScrollBar", empty_icon);
	theme->set_icon("decrement", "VScrollBar", empty_icon);
	theme->set_icon("decrement_highlight", "VScrollBar", empty_icon);
	theme->set_icon("decrement_pressed", "VScrollBar", empty_icon);
	const Ref<StyleBoxFlat> style_slider = make_flat_stylebox(style_normal_color, 4, 4, 4, 4, 4);
	const Ref<StyleBoxFlat> style_slider_grabber = make_flat_stylebox(style_progress_color, 4, 4, 4, 4, 4);
	const Ref<StyleBoxFlat> style_slider_grabber_highlight = make_flat_stylebox(style_focus_color, 4, 4, 4, 4, 4);
	
	theme->set_stylebox("slider", "HSlider", style_slider);
	theme->set_stylebox("grabber_area", "HSlider", style_slider_grabber);
	theme->set_stylebox("grabber_area_highlight", "HSlider", style_slider_grabber_highlight);
	theme->set_icon("grabber", "HSlider", icons["slider_grabber"]);
	theme->set_icon("grabber_highlight", "HSlider", icons["slider_grabber_hl"]);
	theme->set_icon("grabber_disabled", "HSlider", icons["slider_grabber_disabled"]);
	theme->set_icon("tick", "HSlider", icons["hslider_tick"]);
	theme->set_constant("grabber_offset", "HSlider", 0);
	
	theme->set_stylebox("slider", "VSlider", style_slider);
	theme->set_stylebox("grabber_area", "VSlider", style_slider_grabber);
	theme->set_stylebox("grabber_area_highlight", "VSlider", style_slider_grabber_highlight);
	theme->set_icon("grabber", "VSlider", icons["slider_grabber"]);
	theme->set_icon("grabber_highlight", "VSlider", icons["slider_grabber_hl"]);
	theme->set_icon("grabber_disabled", "VSlider", icons["slider_grabber_disabled"]);
	theme->set_icon("tick", "VSlider", icons["vslider_tick"]);
	theme->set_constant("grabber_offset", "VSlider", 0);
	
	theme->set_icon("updown", "SpinBox", icons["updown"]);