### Godot version

4.0 beta 10

### System information

Windows 11 Vulkan

### Issue description

Looked through the issues list, but couldn't find something like this, sorry in advance if this has already been reported.

There is a few cases (in the pictures below) where list of Actions in Input Map may not always show a scrollbar even if the actions list overflows (I imagine this could also happen for the widget that Input Map uses).

![image](https://user-images.githubusercontent.com/39958198/210003566-cf60dbaf-921f-485b-b0a9-51ffc28d0244.png)

![New Bitmap image](https://user-images.githubusercontent.com/39958198/210004079-8eb2e6a1-0cf5-4a7c-8905-a4e3cfd0ec5d.png)

![image](https://user-images.githubusercontent.com/39958198/210004165-a6b6790b-248a-4f68-b4d0-b44b25afdf4f.png)

![image](https://user-images.githubusercontent.com/39958198/210004537-aca52194-a464-48b9-b818-24782706de45.png)


### Steps to reproduce

The pictures are clearer than anything I could write here: "a picture is worth 1000 words"

### Minimal reproduction project

N/A
theme_cache.custom_button_pressed = get_theme_stylebox(SNAME("custom_button_pressed"));
	theme_cache.custom_button_font_highlight = get_theme_color(SNAME("custom_button_font_highlight"));
	theme_cache.font_color = get_theme_color(SNAME("font_color"));
	theme_cache.font_selected_color = get_theme_color(SNAME("font_selected_color"));
	theme_cache.drop_position_color = get_theme_color(SNAME("drop_position_color"));
	theme_cache.h_separation = get_theme_constant(SNAME("h_separation"));
	theme_cache.v_separation = get_theme_constant(SNAME("v_separation"));
	theme_cache.item_margin = get_theme_constant(SNAME("item_margin"));
	theme_cache.button_margin = get_theme_constant(SNAME("button_margin"));
	theme_cache.font_outline_color = get_theme_color(SNAME("font_outline_color"));
	theme_cache.font_outline_size = get_theme_constant(SNAME("outline_size"));
	theme_cache.draw_guides = get_theme_constant(SNAME("draw_guides"));
	theme_cache.guide_color = get_theme_color(SNAME("guide_color"));
	theme_cache.draw_relationship_lines = get_theme_constant(SNAME("draw_relationship_lines"));
	theme_cache.relationship_line_width = get_theme_constant(SNAME("relationship_line_width"));
	theme_cache.parent_hl_line_width = get_theme_constant(SNAME("parent_hl_line_width"));
	theme_cache.children_hl_line_width = get_theme_constant(SNAME("children_hl_line_width"));
	theme_cache.parent_hl_line_margin = get_theme_constant(SNAME("parent_hl_line_margin"));
	theme_cache.relationship_line_color = get_theme_color(SNAME("relationship_line_color"));
	theme_cache.parent_hl_line_color = get_theme_color(SNAME("parent_hl_line_color"));
	theme_cache.children_hl_line_color = get_theme_color(SNAME("children_hl_line_color"));
	theme_cache.scroll_border = get_theme_constant(SNAME("scroll_border"));
	theme_cache.scroll_speed = get_theme_constant(SNAME("scroll_speed"));
	theme_cache.title_button = get_theme_stylebox(SNAME("title_button_normal"));
	theme_cache.title_button_pressed = get_theme_stylebox(SNAME("title_button_pressed"));
	theme_cache.title_button_hover = get_theme_stylebox(SNAME("title_button_hover"));
	theme_cache.title_button_color = get_theme_color(SNAME("title_button_color"));
	theme_cache.base_scale = get_theme_default_base_scale();
}
int Tree::compute_item_height(TreeItem *p_item) const {