settings_ui: Add theme settings controls (#15115)

This PR adds settings controls for the theme settings.

Release Notes:

- N/A

crates/ui/src/components/dropdown_menu.rs

@@ -42,8 +42,9 @@ impl Disableable for DropdownMenu {
 impl RenderOnce for DropdownMenu {
     fn render(self, _cx: &mut WindowContext) -> impl IntoElement {
         PopoverMenu::new(self.id)
+            .full_width(self.full_width)
             .menu(move |_cx| Some(self.menu.clone()))
-            .trigger(DropdownMenuTrigger::new(self.label))
+            .trigger(DropdownMenuTrigger::new(self.label).full_width(self.full_width))
     }
 }
 
@@ -68,6 +69,11 @@ impl DropdownMenuTrigger {
             on_click: None,
         }
     }
+
+    pub fn full_width(mut self, full_width: bool) -> Self {
+        self.full_width = full_width;
+        self
+    }
 }
 
 impl Disableable for DropdownMenuTrigger {

crates/ui/src/components/numeric_stepper.rs

@@ -7,6 +7,8 @@ pub struct NumericStepper {
     value: SharedString,
     on_decrement: Box<dyn Fn(&ClickEvent, &mut WindowContext) + 'static>,
     on_increment: Box<dyn Fn(&ClickEvent, &mut WindowContext) + 'static>,
+    /// Whether to reserve space for the reset button.
+    reserve_space_for_reset: bool,
     on_reset: Option<Box<dyn Fn(&ClickEvent, &mut WindowContext) + 'static>>,
 }
 
@@ -20,10 +22,16 @@ impl NumericStepper {
             value: value.into(),
             on_decrement: Box::new(on_decrement),
             on_increment: Box::new(on_increment),
+            reserve_space_for_reset: false,
             on_reset: None,
         }
     }
 
+    pub fn reserve_space_for_reset(mut self, reserve_space_for_reset: bool) -> Self {
+        self.reserve_space_for_reset = reserve_space_for_reset;
+        self
+    }
+
     pub fn on_reset(
         mut self,
         on_reset: impl Fn(&ClickEvent, &mut WindowContext) + 'static,
@@ -48,13 +56,15 @@ impl RenderOnce for NumericStepper {
                             .icon_size(icon_size)
                             .on_click(on_reset),
                     )
-                } else {
+                } else if self.reserve_space_for_reset {
                     element.child(
                         h_flex()
                             .size(icon_size.square(cx))
                             .flex_none()
                             .into_any_element(),
                     )
+                } else {
+                    element
                 }
             })
             .child(

crates/ui/src/components/popover_menu.rs

@@ -1,10 +1,10 @@
 use std::{cell::RefCell, rc::Rc};
 
 use gpui::{
-    anchored, deferred, div, point, prelude::FluentBuilder, px, AnchorCorner, AnyElement, Bounds,
-    DismissEvent, DispatchPhase, Element, ElementId, GlobalElementId, HitboxId, InteractiveElement,
-    IntoElement, LayoutId, ManagedView, MouseDownEvent, ParentElement, Pixels, Point, View,
-    VisualContext, WindowContext,
+    anchored, deferred, div, point, prelude::FluentBuilder, px, size, AnchorCorner, AnyElement,
+    Bounds, DismissEvent, DispatchPhase, Element, ElementId, GlobalElementId, HitboxId,
+    InteractiveElement, IntoElement, LayoutId, Length, ManagedView, MouseDownEvent, ParentElement,
+    Pixels, Point, Style, View, VisualContext, WindowContext,
 };
 
 use crate::prelude::*;
@@ -74,6 +74,7 @@ pub struct PopoverMenu<M: ManagedView> {
     attach: Option<AnchorCorner>,
     offset: Option<Point<Pixels>>,
     trigger_handle: Option<PopoverMenuHandle<M>>,
+    full_width: bool,
 }
 
 impl<M: ManagedView> PopoverMenu<M> {
@@ -87,9 +88,15 @@ impl<M: ManagedView> PopoverMenu<M> {
             attach: None,
             offset: None,
             trigger_handle: None,
+            full_width: false,
         }
     }
 
+    pub fn full_width(mut self, full_width: bool) -> Self {
+        self.full_width = full_width;
+        self
+    }
+
     pub fn menu(mut self, f: impl Fn(&mut WindowContext) -> Option<View<M>> + 'static) -> Self {
         self.menu_builder = Some(Rc::new(f));
         self
@@ -258,10 +265,13 @@ impl<M: ManagedView> Element for PopoverMenu<M> {
                     .as_mut()
                     .map(|child_element| child_element.request_layout(cx));
 
-                let layout_id = cx.request_layout(
-                    gpui::Style::default(),
-                    menu_layout_id.into_iter().chain(child_layout_id),
-                );
+                let mut style = Style::default();
+                if self.full_width {
+                    style.size = size(relative(1.).into(), Length::Auto);
+                }
+
+                let layout_id =
+                    cx.request_layout(style, menu_layout_id.into_iter().chain(child_layout_id));
 
                 (
                     (