### 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_color("font_selected_color", "TabContainer", control_font_hover_color);
	theme->set_color("font_unselected_color", "TabContainer", control_font_low_color);
	theme->set_color("font_disabled_color", "TabContainer", control_font_disabled_color);
	theme->set_color("font_outline_color", "TabContainer", Color(1, 1, 1));
	theme->set_color("drop_mark_color", "TabContainer", Color(1, 1, 1));
	theme->set_constant("side_margin", "TabContainer", 8 * scale);
	theme->set_constant("icon_separation", "TabContainer", 4 * scale);
	theme->set_constant("outline_size", "TabContainer", 0);
	
	theme->set_stylebox("tab_selected", "TabBar", style_tab_selected);
	theme->set_stylebox("tab_unselected", "TabBar", style_tab_unselected);
	theme->set_stylebox("tab_disabled", "TabBar", style_tab_disabled);
	theme->set_stylebox("button_pressed", "TabBar", button_pressed);
	theme->set_stylebox("button_highlight", "TabBar", button_normal);
	theme->set_icon("increment", "TabBar", icons["scroll_button_right"]);
	theme->set_icon("increment_highlight", "TabBar", icons["scroll_button_right_hl"]);
	theme->set_icon("decrement", "TabBar", icons["scroll_button_left"]);
	theme->set_icon("decrement_highlight", "TabBar", icons["scroll_button_left_hl"]);
	theme->set_icon("drop_mark", "TabBar", icons["tabs_drop_mark"]);
	theme->set_icon("close", "TabBar", icons["close"]);
	theme->set_font("font", "TabBar", Ref<Font>());
	theme->set_font_size("font_size", "TabBar", -1);
	theme->set_color("font_selected_color", "TabBar", control_font_hover_color);
	theme->set_color("font_unselected_color", "TabBar", control_font_low_color);
	theme->set_color("font_disabled_color", "TabBar", control_font_disabled_color);
	theme->set_color("font_outline_color", "TabBar", Color(1, 1, 1));
	theme->set_color("drop_mark_color", "TabBar", Color(1, 1, 1));
	theme->set_constant("h_separation", "TabBar", 4 * scale);
	theme->set_constant("outline_size", "TabBar", 0);