Try tweaking settings/theme for Windows. Setting the theme didn't work.

src-tauri/src/lib.rs

@@ -1818,7 +1818,7 @@ fn create_window(handle: &AppHandle, url: &str) -> WebviewWindow {
             .resizable(true)
             .fullscreen(false)
             .disable_drag_drop_handler() // Required for frontend Dnd on windows
-            .inner_size(DEFAULT_WINDOW_WIDTH as f64, DEFAULT_WINDOW_HEIGHT as f64)
+            .inner_size(DEFAULT_WINDOW_WIDTH, DEFAULT_WINDOW_HEIGHT)
             .position(
                 // Randomly offset so windows don't stack exactly
                 100.0 + random::<f64>() * 30.0,
@@ -1839,7 +1839,7 @@ fn create_window(handle: &AppHandle, url: &str) -> WebviewWindow {
     #[cfg(not(target_os = "macos"))]
     {
         // Doesn't seem to work from Rust, here, so we do it in main.tsx
-        // win_builder = win_builder.decorations(false);
+        win_builder = win_builder.decorations(false);
     }
 
     let win = win_builder.build().expect("failed to build window");

src-tauri/src/tauri_plugin_windows_window.rs

@@ -1,20 +1,21 @@
 use hex_color::HexColor;
-use tauri::{ Runtime, Window};
+use tauri::{Manager, Runtime, Window, WindowEvent};
 
 use std::mem::transmute;
-use std::{ptr, ffi::c_void, mem::size_of};
+use std::{ffi::c_void, mem::size_of, ptr};
 use tauri::plugin::{Builder, TauriPlugin};
 
-use windows::Win32::UI::Controls::{WTA_NONCLIENT, WTNCA_NODRAWICON, WTNCA_NOSYSMENU, WTNCA_NOMIRRORHELP};
+use windows::Win32::UI::Controls::{
+    WTA_NONCLIENT, WTNCA_NODRAWICON, WTNCA_NOMIRRORHELP, WTNCA_NOSYSMENU,
+};
 
+use windows::Win32::Foundation::COLORREF;
+use windows::Win32::Foundation::{BOOL, HWND};
+use windows::Win32::Graphics::Dwm::DwmSetWindowAttribute;
+use windows::Win32::Graphics::Dwm::DWMWA_CAPTION_COLOR;
+use windows::Win32::Graphics::Dwm::DWMWA_USE_IMMERSIVE_DARK_MODE;
 use windows::Win32::UI::Controls::SetWindowThemeAttribute;
 use windows::Win32::UI::Controls::WTNCA_NODRAWCAPTION;
-use windows::Win32::Graphics::Dwm::DWMWA_CAPTION_COLOR;
-use windows::Win32::Foundation::COLORREF;
-use windows::Win32::Foundation::BOOL;
-use windows::Win32::Graphics::Dwm::DwmSetWindowAttribute;
-use windows::Win32::Foundation::HWND;
-use windows::Win32::Graphics::Dwm::{DWMWA_USE_IMMERSIVE_DARK_MODE};
 
 pub fn init<R: Runtime>() -> TauriPlugin<R> {
     Builder::new("windows_window")
@@ -28,19 +29,18 @@ pub fn init<R: Runtime>() -> TauriPlugin<R> {
 
 fn hex_color_to_colorref(color: HexColor) -> COLORREF {
     // TODO: Remove this unsafe, This operation doesn't need to be unsafe!
-    unsafe {
-        COLORREF(transmute::<[u8; 4], u32>([color.r, color.g, color.b, 0]))
-    }
+    unsafe { COLORREF(transmute::<[u8; 4], u32>([color.r, color.g, color.b, 0])) }
 }
 
 struct WinThemeAttribute {
+    #[allow(dead_code)]
     flag: u32,
-    mask: u32
+    #[allow(dead_code)]
+    mask: u32,
 }
 
 #[cfg(target_os = "windows")]
 fn update_bg_color(hwnd: &HWND, bg_color: HexColor) {
-
     let use_dark_mode = BOOL::from(true);
 
     let final_color = hex_color_to_colorref(bg_color);
@@ -50,26 +50,29 @@ fn update_bg_color(hwnd: &HWND, bg_color: HexColor) {
             HWND(hwnd.0),
             DWMWA_USE_IMMERSIVE_DARK_MODE,
             ptr::addr_of!(use_dark_mode) as *const c_void,
-            size_of::<BOOL>().try_into().unwrap()
-        ).unwrap();
+            size_of::<BOOL>().try_into().unwrap(),
+        )
+        .unwrap();
 
         DwmSetWindowAttribute(
             HWND(hwnd.0),
             DWMWA_CAPTION_COLOR,
             ptr::addr_of!(final_color) as *const c_void,
-            size_of::<COLORREF>().try_into().unwrap()
-        ).unwrap();
+            size_of::<COLORREF>().try_into().unwrap(),
+        )
+        .unwrap();
 
         let flags = WTNCA_NODRAWCAPTION | WTNCA_NODRAWICON;
-        let mask  = WTNCA_NODRAWCAPTION | WTNCA_NODRAWICON | WTNCA_NOSYSMENU | WTNCA_NOMIRRORHELP;
+        let mask = WTNCA_NODRAWCAPTION | WTNCA_NODRAWICON | WTNCA_NOSYSMENU | WTNCA_NOMIRRORHELP;
         let options = WinThemeAttribute { flag: flags, mask };
 
         SetWindowThemeAttribute(
             HWND(hwnd.0),
             WTA_NONCLIENT,
             ptr::addr_of!(options) as *const c_void,
-            size_of::<WinThemeAttribute>().try_into().unwrap()
-        ).unwrap();
+            size_of::<WinThemeAttribute>().try_into().unwrap(),
+        )
+        .unwrap();
     }
 }
 
@@ -78,12 +81,17 @@ pub fn setup_win_window<R: Runtime>(window: Window<R>) {
     let win_handle = window.hwnd().unwrap();
     let win_clone = win_handle.clone();
 
-    window.listen_global("yaak_bg_changed", move |ev| {
-        let payload = serde_json::from_str::<&str>(ev.payload().unwrap())
-            .unwrap()
-            .trim();
-
+    let event_id = window.listen("yaak_bg_changed", move |ev| {
+        let payload = serde_json::from_str::<&str>(ev.payload()).unwrap().trim();
         let color = HexColor::parse_rgb(payload).unwrap();
         update_bg_color(&HWND(win_clone.0), color);
     });
+
+    let h = window.app_handle().clone();
+    window.on_window_event(move |e| match e {
+        WindowEvent::Destroyed => {
+            h.unlisten(event_id);
+        }
+        _ => {}
+    })
 }