windows: do not show border radius

[maldag]

I didn't find a way to create a window in windows without border radius on windows without using frameless-Mode. Using frameless-mode the window will have corners, but I need the title bar and a movable widget.
Is there a way to get this working on windows?

Update1:

I fiddled around in the code a bit and found a way to accomplish this:

diff --git a/windows/window_manager.cpp b/windows/window_manager.cpp
index a27fc4f..cda998d 100644
--- a/windows/window_manager.cpp
+++ b/windows/window_manager.cpp
@@ -755,6 +755,12 @@ void WindowManager::SetBounds(const flutter::EncodableMap& args) {
   }
 
   SetWindowPos(hwnd, HWND_TOP, x, y, width, height, uFlags);
+  DWM_WINDOW_CORNER_PREFERENCE cornerPreference = DWM_WINDOW_CORNER_PREFERENCE::DWMWCP_DONOTROUND;
+  DwmSetWindowAttribute(hwnd,
+    DWMWA_WINDOW_CORNER_PREFERENCE,
+    &cornerPreference,
+    sizeof(cornerPreference)
+  );
 }

So my question would no be how this could be included in a proper way by the maintainers?

The window is still smaller as the size given, it seems to me it's subtracting some pixels for the corner ...