Action release handlers (#8782)

This PR adds support for handling action releases — events that
are fired when the user releases all the modifier keys that were part of
an action-triggering shortcut.

If the user holds modifiers and invokes several actions sequentially via
shortcuts (same or different), only the last action is "released" when
its modifier keys released.

~The following methods were added to `Div`:~
- ~`capture_action_release()`~
- ~`on_action_release()`~
- ~`on_boxed_action_release()`~

~They work similarly to `capture_action()`, `on_action()` and
`on_boxed_action()`.~

See the implementation details in [this
comment](https://github.com/zed-industries/zed/pull/8782#issuecomment-2009154646).

Release Notes:

- Added a fast-switch mode to the file finder: hit `p` or `shift-p`
while holding down `cmd` to select a file immediately. (#8258).

Related Issues:

- Implements #8757 
- Implements #8258
- Part of #7653 

Co-authored-by: @ConradIrwin

crates/gpui/src/window/element_cx.rs

@@ -33,10 +33,11 @@ use crate::{
     ContentMask, Corners, CursorStyle, DevicePixels, DispatchNodeId, DispatchPhase, DispatchTree,
     DrawPhase, ElementId, ElementStateBox, EntityId, FocusHandle, FocusId, FontId, GlobalElementId,
     GlyphId, Hsla, ImageData, InputHandler, IsZero, KeyContext, KeyEvent, LayoutId,
-    LineLayoutIndex, MonochromeSprite, MouseEvent, PaintQuad, Path, Pixels, PlatformInputHandler,
-    Point, PolychromeSprite, Quad, RenderGlyphParams, RenderImageParams, RenderSvgParams, Scene,
-    Shadow, SharedString, Size, StrikethroughStyle, Style, TextStyleRefinement,
-    TransformationMatrix, Underline, UnderlineStyle, Window, WindowContext, SUBPIXEL_VARIANTS,
+    LineLayoutIndex, ModifiersChangedEvent, MonochromeSprite, MouseEvent, PaintQuad, Path, Pixels,
+    PlatformInputHandler, Point, PolychromeSprite, Quad, RenderGlyphParams, RenderImageParams,
+    RenderSvgParams, Scene, Shadow, SharedString, Size, StrikethroughStyle, Style,
+    TextStyleRefinement, TransformationMatrix, Underline, UnderlineStyle, Window, WindowContext,
+    SUBPIXEL_VARIANTS,
 };
 
 pub(crate) type AnyMouseListener =
@@ -1324,4 +1325,22 @@ impl<'a> ElementContext<'a> {
             },
         ));
     }
+
+    /// Register a modifiers changed event listener on the window for the next frame.
+    ///
+    /// This is a fairly low-level method, so prefer using event handlers on elements unless you have
+    /// a specific need to register a global listener.
+    pub fn on_modifiers_changed(
+        &mut self,
+        listener: impl Fn(&ModifiersChangedEvent, &mut ElementContext) + 'static,
+    ) {
+        self.window
+            .next_frame
+            .dispatch_tree
+            .on_modifiers_changed(Rc::new(
+                move |event: &ModifiersChangedEvent, cx: &mut ElementContext<'_>| {
+                    listener(event, cx)
+                },
+            ));
+    }
 }