### 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("focus", "TextEdit", focus);
	theme->set_stylebox("read_only", "TextEdit", style_line_edit_read_only);
	theme->set_icon("tab", "TextEdit", icons["text_edit_tab"]);
	theme->set_icon("space", "TextEdit", icons["text_edit_space"]);
	theme->set_font("font", "TextEdit", Ref<Font>());
	theme->set_font_size("font_size", "TextEdit", -1);
	theme->set_color("background_color", "TextEdit", Color(0, 0, 0, 0));
	theme->set_color("font_color", "TextEdit", control_font_color);
	theme->set_color("font_selected_color", "TextEdit", Color(0, 0, 0, 0));
	theme->set_color("font_readonly_color", "TextEdit", control_font_disabled_color);
	theme->set_color("font_placeholder_color", "TextEdit", control_font_placeholder_color);
	theme->set_color("font_outline_color", "TextEdit", Color(1, 1, 1));
	theme->set_color("selection_color", "TextEdit", control_selection_color);
	theme->set_color("current_line_color", "TextEdit", Color(0.25, 0.25, 0.26, 0.8));
	theme->set_color("caret_color", "TextEdit", control_font_color);
	theme->set_color("caret_background_color", "TextEdit", Color(0, 0, 0));
	theme->set_color("word_highlighted_color", "TextEdit", Color(0.5, 0.5, 0.5, 0.25));
	theme->set_color("search_result_color", "TextEdit", Color(0.3, 0.3, 0.3));
	theme->set_color("search_result_border_color", "TextEdit", Color(0.3, 0.3, 0.3, 0.4));
	theme->set_constant("line_spacing", "TextEdit", 4 * scale);
	theme->set_constant("outline_size", "TextEdit", 0);
	theme->set_constant("caret_width", "TextEdit", 1);
	
	theme->set_stylebox("normal", "CodeEdit", style_line_edit);
	theme->set_stylebox("focus", "CodeEdit", focus);
	theme->set_stylebox("read_only", "CodeEdit", style_line_edit_read_only);
	theme->set_stylebox("completion", "CodeEdit", make_flat_stylebox(style_normal_color, 0, 0, 0, 0));
	theme->set_icon("tab", "CodeEdit", icons["text_edit_tab"]);
	theme->set_icon("space", "CodeEdit", icons["text_edit_space"]);
	theme->set_icon("breakpoint", "CodeEdit", icons["breakpoint"]);