[AlwaysOnTop] Round corners on Windows 11 (#19109)

* check window corners

* draw rounded rectangle

* draw rounded corners

* switch between rounded and not rounded rects

* added enabled corners setting

* update corner

src/modules/alwaysontop/AlwaysOnTop/WindowCornersUtil.cpp

@@ -0,0 +1,39 @@
+#include "pch.h"
+#include "WindowCornersUtil.h"
+
+#include <common/utils/winapi_error.h>
+
+#include <dwmapi.h>
+
+// Placeholder enums since dwmapi.h doesn't have these until SDK 22000.
+// TODO: Remove once SDK targets 22000 or above.
+enum DWMWINDOWATTRIBUTE_CUSTOM
+{
+    DWMWA_WINDOW_CORNER_PREFERENCE = 33
+};
+
+enum DWM_WINDOW_CORNER_PREFERENCE
+{
+    DWMWCP_DEFAULT = 0,
+    DWMWCP_DONOTROUND = 1,
+    DWMWCP_ROUND = 2,
+    DWMWCP_ROUNDSMALL = 3
+};
+
+bool WindowBordersUtils::AreCornersRounded(HWND window) noexcept
+{
+    int cornerPreference = DWMWCP_DEFAULT;
+    auto res = DwmGetWindowAttribute(window, DWMWA_WINDOW_CORNER_PREFERENCE, &cornerPreference, sizeof(cornerPreference));
+    if (res != S_OK)
+    {
+        // no need to spam with error log if arg is invalid (on Windows 10)
+        if (res != E_INVALIDARG)
+        {
+            Logger::error(L"Get corner preference error: {}", get_last_error_or_default(res)); 
+        }
+
+        return false;
+    }
+
+    return cornerPreference != DWM_WINDOW_CORNER_PREFERENCE::DWMWCP_DONOTROUND;
+}