### 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
p_sbox->set_expand_margin_size(SIDE_LEFT, p_left * scale);
	p_sbox->set_expand_margin_size(SIDE_TOP, p_top * scale);
	p_sbox->set_expand_margin_size(SIDE_RIGHT, p_right * scale);
	p_sbox->set_expand_margin_size(SIDE_BOTTOM, p_bottom * scale);
	return p_sbox;
}
static Ref<ImageTexture> generate_icon(int p_index) {
	Ref<Image> img = memnew(Image);
#ifdef MODULE_SVG_ENABLED
	
	
	
	const bool upsample = !Math::is_equal_approx(Math::round(scale), scale);
	ImageLoaderSVG img_loader;
	Error err = img_loader.create_image_from_string(img, default_theme_icons_sources[p_index], scale, upsample, HashMap<Color, Color>());
	ERR_FAIL_COND_V_MSG(err != OK, Ref<ImageTexture>(), "Failed generating icon, unsupported or invalid SVG data in default theme.");
#endif
	return ImageTexture::create_from_image(img);
}
static Ref<StyleBox> make_empty_stylebox(float p_margin_left = -1, float p_margin_top = -1, float p_margin_right = -1, float p_margin_bottom = -1) {