linux: Fix buttons clicks wouldn’t work on startup until clicked on center pane (#34590)

Closes #31805

This is an issue with Linux currently that `window.focus` is `None` upon
startup in both X11 and Wayland. Specifically, the order in which
[this](8d05a3d389/crates/gpui/src/window.rs (L3116))
and
[this](8d05a3d389/crates/gpui/src/app.rs (L956))
are executed varies between Linux and macOS. That is, one tries to
remove (blur) focus from a window, while other checks window focus to
put that focus id to a frame. In macOS, blur happens afterwards setting
focus on a frame, but in Linux, the inverse of it happens, leading to
`window.focus` to `None`.

For the time being, we handle all visible buttons to take care of this
**focus can be `None`** case, and make it work anyway. But, we should
look at the deeper issue mentioned above with GPUI. Created new issue to
track that https://github.com/zed-industries/zed/issues/34591.

Release Notes:

- Fixed an issue where button clicks wouldn’t work on startup until
clicked on the center pane on Linux.

crates/title_bar/src/title_bar.rs

@@ -22,9 +22,9 @@ use auto_update::AutoUpdateStatus;
 use call::ActiveCall;
 use client::{Client, UserStore};
 use gpui::{
-    Action, AnyElement, App, Context, Corner, Element, Entity, InteractiveElement, IntoElement,
-    MouseButton, ParentElement, Render, StatefulInteractiveElement, Styled, Subscription,
-    WeakEntity, Window, actions, div,
+    Action, AnyElement, App, Context, Corner, Element, Entity, Focusable, InteractiveElement,
+    IntoElement, MouseButton, ParentElement, Render, StatefulInteractiveElement, Styled,
+    Subscription, WeakEntity, Window, actions, div,
 };
 use onboarding_banner::OnboardingBanner;
 use project::Project;
@@ -504,7 +504,8 @@ impl TitleBar {
                     )
                 })
                 .on_click(move |_, window, cx| {
-                    let _ = workspace.update(cx, |_this, cx| {
+                    let _ = workspace.update(cx, |this, cx| {
+                        window.focus(&this.active_pane().focus_handle(cx));
                         window.dispatch_action(zed_actions::git::Branch.boxed_clone(), cx);
                     });
                 })