feat: full-saturation slider tracks while the window is focused

The dissolved root backplate's translucent plate normally draws OVER
the slider gradients (the muted pastel wash). While the window holds
keyboard focus the plate now drops UNDER them, so the tracks show
unwashed color while the picker is in use; unfocusing restores the
wash. Uses cce-ui's new handle_focus_change hook.

Co-Authored-By: Claude Fable 5 <[email protected]>

 src/main.rs | 35 +++++++++++++++++++++++++++++------
 1 file changed, 29 insertions(+), 6 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 6c1e3f2..2e5e431 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -349,6 +349,10 @@ struct ColorApp {
     // so the caller can restore the launch value.
     stream: bool,
     last_streamed: String,
+    // Keyboard focus: while focused the backplate wash drops UNDER the
+    // sliders so the tracks show full-saturation color; unfocused keeps the
+    // muted washed-over look.
+    window_focused: bool,
 
     cursor_x: f32,
     cursor_y: f32,
@@ -495,22 +499,32 @@ impl ColorApp {
         // gradient quads first, then the dissolved root Backplate's translucent plate OVER
         // them (the legacy aggregate emitted all plain quads, then the rounded root bg —
         // the app's muted pastel look depends on that wash), then the rounded buttons.
+        // Focused windows invert the first two: the plate goes UNDER the sliders so the
+        // tracks show unwashed full-saturation color while the picker is being used.
         let mut window_pc = PageContent::new();
         {
             let self_ptr = self as *mut Self;
+            // Backplate::color() default: page-low at the active backplate opacity.
+            let backplate = {
+                let mut c = cce_ui::color::page_low_color();
+                if c[3] > 0.001 {
+                    c[3] = cce_ui::color::active_backplate_opacity();
+                }
+                let radius = cce_ui::colors::backplate_corner_radius();
+                (c, 0.0, 0.0, self.width as f32, self.height as f32, radius.max(0.0), (radius > 0.1, radius > 0.1, radius > 0.1, radius > 0.1))
+            };
+            if self.window_focused {
+                window_pc.rects.push(backplate);
+            }
             unsafe {
                 for slider in (*self_ptr).sliders.iter_mut() {
                     let (x, y, w, h) = slider.rect();
                     cce_ui::layout::render_widget(&mut window_pc, slider, x, y, w, h, &mut self.ui_context);
                 }
             }
-            // Backplate::color() default: page-low at the active backplate opacity.
-            let mut c = cce_ui::color::page_low_color();
-            if c[3] > 0.001 {
-                c[3] = cce_ui::color::active_backplate_opacity();
+            if !self.window_focused {
+                window_pc.rects.push(backplate);
             }
-            let radius = cce_ui::colors::backplate_corner_radius();
-            window_pc.rects.push((c, 0.0, 0.0, self.width as f32, self.height as f32, radius.max(0.0), (radius > 0.1, radius > 0.1, radius > 0.1, radius > 0.1)));
             unsafe {
                 if self.expecting_output {
                     let (x, y, w, h) = (*self_ptr).apply_btn.rect();
@@ -683,6 +697,7 @@ impl Application for ColorApp {
             expecting_output,
             stream,
             last_streamed: String::new(),
+            window_focused: false,
             cursor_x: 0.0,
             cursor_y: 0.0,
             width: initial_w,
@@ -954,6 +969,14 @@ impl Application for ColorApp {
         }
         None
     }
+
+    fn handle_focus_change(&mut self, focused: bool, needs_rebuild: &mut bool) {
+        if self.window_focused != focused {
+            self.window_focused = focused;
+            self.rebuild_layout();
+            *needs_rebuild = true;
+        }
+    }
 }
 
 // ── Color Utilities ──────────────────────────────────────────────────