Reapply Windows borderless styling without hiding taskbar entry

app/app.py

@@ -5,6 +5,7 @@ from __future__ import annotations
 import ctypes
 import platform
 import tkinter as tk
+from ctypes import wintypes
 from importlib import resources
 
 from .gui import ColorPickerMixin, ExclusionMixin, ThemeMixin, UIBuilderMixin
@@ -84,9 +85,17 @@ class ICRAApp(
         default_y = (screen_height - default_height) // 4
         self._window_geometry = f"{default_width}x{default_height}+{default_x}+{default_y}"
         self._is_maximized = True
+        self._use_overrideredirect = platform.system() != "Windows"
         self.root.geometry(f"{screen_width}x{screen_height}+0+0")
         self.root.configure(bg="#f2f2f7")
-        self.root.overrideredirect(True)
+        try:
+            self.root.overrideredirect(self._use_overrideredirect)
+        except Exception:
+            if self._use_overrideredirect:
+                try:
+                    self.root.attributes("-type", "splash")
+                except Exception:
+                    pass
         self._window_icon_ref = None
         self._apply_window_icon()
         self._init_window_chrome()
@@ -145,22 +154,74 @@ class ICRAApp(
     def _init_window_chrome(self) -> None:
         """Configure a borderless window while retaining a taskbar entry."""
         try:
-            self.root.bind("<Map>", self._restore_borderless)
+            if platform.system() == "Windows":
-            self.root.after(0, self._restore_borderless)
+                self.root.after(0, self._ensure_taskbar_entry)
-            self.root.after(0, self._ensure_taskbar_entry)
+                self.root.after(0, self._apply_windows_borderless_style)
+                self.root.bind("<Map>", lambda _e: self._apply_windows_borderless_style(), add="+")
+                self.root.bind("<Map>", lambda _e: self._ensure_taskbar_entry(), add="+")
+            else:
+                self.root.bind("<Map>", self._restore_borderless)
+                self.root.after(0, self._restore_borderless)
+                self.root.after(0, self._ensure_taskbar_entry)
         except Exception:
-            try:
+            pass
-                self.root.overrideredirect(True)
-            except Exception:
-                pass
 
     def _restore_borderless(self, _event=None) -> None:
         try:
-            self.root.overrideredirect(True)
+            if self._use_overrideredirect:
+                self.root.overrideredirect(True)
             self._ensure_taskbar_entry()
         except Exception:
             pass
 
+    def _apply_windows_borderless_style(self) -> None:
+        try:
+            if platform.system() != "Windows":
+                return
+
+            hwnd = self.root.winfo_id()
+            if not hwnd:
+                self.root.after(50, self._apply_windows_borderless_style)
+                return
+
+            user32 = ctypes.windll.user32  # type: ignore[attr-defined]
+            GWL_STYLE = -16
+            WS_CAPTION = 0x00C00000
+            WS_THICKFRAME = 0x00040000
+            WS_MINIMIZEBOX = 0x00020000
+            WS_MAXIMIZEBOX = 0x00010000
+            WS_SYSMENU = 0x00080000
+            SWP_NOSIZE = 0x0001
+            SWP_NOMOVE = 0x0002
+            SWP_NOZORDER = 0x0004
+            SWP_FRAMECHANGED = 0x0020
+
+            set_window_long = getattr(user32, "SetWindowLongPtrW", user32.SetWindowLongW)
+            get_window_long = getattr(user32, "GetWindowLongPtrW", user32.GetWindowLongW)
+            ptr_type = ctypes.c_longlong if ctypes.sizeof(ctypes.c_void_p) == 8 else ctypes.c_long
+            get_window_long.restype = ptr_type  # type: ignore[attr-defined]
+            get_window_long.argtypes = [wintypes.HWND, ctypes.c_int]  # type: ignore[attr-defined]
+            set_window_long.restype = ptr_type  # type: ignore[attr-defined]
+            set_window_long.argtypes = [wintypes.HWND, ctypes.c_int, ptr_type]  # type: ignore[attr-defined]
+
+            style = get_window_long(hwnd, GWL_STYLE)
+            new_style = style & ~(
+                WS_CAPTION | WS_THICKFRAME | WS_MINIMIZEBOX | WS_MAXIMIZEBOX | WS_SYSMENU
+            )
+            if new_style != style:
+                set_window_long(hwnd, GWL_STYLE, ptr_type(new_style))
+                user32.SetWindowPos(
+                    hwnd,
+                    0,
+                    0,
+                    0,
+                    0,
+                    0,
+                    SWP_NOMOVE | SWP_NOSIZE | SWP_NOZORDER | SWP_FRAMECHANGED,
+                )
+        except Exception:
+            pass
+
 
 def start_app() -> None:
     """Entry point used by the CLI script."""

app/gui/ui.py

@@ -566,17 +566,19 @@ class UIBuilderMixin:
     def _minimize_window(self) -> None:
         try:
             self._remember_window_geometry()
-            if hasattr(self.root, "overrideredirect"):
+            use_or = getattr(self, "_use_overrideredirect", False)
+            if use_or and hasattr(self.root, "overrideredirect"):
                 try:
                     self.root.overrideredirect(False)
                 except Exception:
                     pass
             self.root.iconify()
-            restorer = getattr(self, "_restore_borderless", None)
+            if use_or:
-            if callable(restorer):
+                restorer = getattr(self, "_restore_borderless", None)
-                self.root.after(120, restorer)
+                if callable(restorer):
-            elif hasattr(self.root, "overrideredirect"):
+                    self.root.after(120, restorer)
-                self.root.after(120, lambda: self.root.overrideredirect(True))  # type: ignore[arg-type]
+                elif hasattr(self.root, "overrideredirect"):
+                    self.root.after(120, lambda: self.root.overrideredirect(True))  # type: ignore[arg-type]
         except Exception:
             pass