### 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_icon("bookmark", "CodeEdit", icons["bookmark"]);
	theme->set_icon("executing_line", "CodeEdit", icons["arrow_right"]);
	theme->set_icon("can_fold", "CodeEdit", icons["arrow_down"]);
	theme->set_icon("folded", "CodeEdit", icons["arrow_right"]);
	theme->set_icon("folded_eol_icon", "CodeEdit", icons["text_edit_ellipsis"]);
	theme->set_font("font", "CodeEdit", Ref<Font>());
	theme->set_font_size("font_size", "CodeEdit", -1);
	theme->set_color("background_color", "CodeEdit", Color(0, 0, 0, 0));
	theme->set_color("completion_background_color", "CodeEdit", Color(0.17, 0.16, 0.2));
	theme->set_color("completion_selected_color", "CodeEdit", Color(0.26, 0.26, 0.27));
	theme->set_color("completion_existing_color", "CodeEdit", Color(0.87, 0.87, 0.87, 0.13));
	theme->set_color("completion_scroll_color", "CodeEdit", control_font_pressed_color * Color(1, 1, 1, 0.29));
	theme->set_color("completion_scroll_hovered_color", "CodeEdit", control_font_pressed_color * Color(1, 1, 1, 0.4));
	theme->set_color("completion_font_color", "CodeEdit", Color(0.67, 0.67, 0.67));
	theme->set_color("font_color", "CodeEdit", control_font_color);
	theme->set_color("font_selected_color", "CodeEdit", Color(0, 0, 0, 0));
	theme->set_color("font_readonly_color", "CodeEdit", Color(control_font_color.r, control_font_color.g, control_font_color.b, 0.5f));
	theme->set_color("font_placeholder_color", "CodeEdit", control_font_placeholder_color);
	theme->set_color("font_outline_color", "CodeEdit", Color(1, 1, 1));
	theme->set_color("selection_color", "CodeEdit", control_selection_color);
	theme->set_color("bookmark_color", "CodeEdit", Color(0.5, 0.64, 1, 0.8));
	theme->set_color("breakpoint_color", "CodeEdit", Color(0.9, 0.29, 0.3));
	theme->set_color("executing_line_color", "CodeEdit", Color(0.98, 0.89, 0.27));
	theme->set_color("current_line_color", "CodeEdit", Color(0.25, 0.25, 0.26, 0.8));
	theme->set_color("code_folding_color", "CodeEdit", Color(0.8, 0.8, 0.8, 0.8));
	theme->set_color("caret_color", "CodeEdit", control_font_color);
	theme->set_color("caret_background_color", "CodeEdit", Color(0, 0, 0));
	theme->set_color("brace_mismatch_color", "CodeEdit", Color(1, 0.2, 0.2));
	theme->set_color("line_number_color", "CodeEdit", Color(0.67, 0.67, 0.67, 0.4));
	theme->set_color("word_highlighted_color", "CodeEdit", Color(0.8, 0.9, 0.9, 0.15));