Spy++ doesn't reach button in Qt application

Question

I'm trying to get the properties of a button but when I drag the spy++'s find window tool it doesn't reach the button (of caption "iniciar gravação" in that case) but rather the button grid parent, like this:

Why is that and how can I get the button properties? I tried with auto it info tool but I get the same behavior.

I tried get that button properties from C# code, like this:

    public class WindowHandleInfo
    {
        private delegate bool EnumWindowProc(IntPtr hwnd, IntPtr lParam);

        [DllImport("user32")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool EnumChildWindows(IntPtr window, EnumWindowProc callback, IntPtr lParam);

        private IntPtr _MainHandle;

        public WindowHandleInfo(IntPtr handle)
        {
            this._MainHandle = handle;
        }

        public List<IntPtr> GetAllChildHandles()
        {
            List<IntPtr> childHandles = new List<IntPtr>();

            GCHandle gcChildhandlesList = GCHandle.Alloc(childHandles);
            IntPtr pointerChildHandlesList = GCHandle.ToIntPtr(gcChildhandlesList);

            try
            {
                EnumWindowProc childProc = new EnumWindowProc(EnumWindow);
                EnumChildWindows(this._MainHandle, childProc, pointerChildHandlesList);
            }
            finally
            {
                gcChildhandlesList.Free();
            }

            return childHandles;
        }

        private bool EnumWindow(IntPtr hWnd, IntPtr lParam)
        {
            GCHandle gcChildhandlesList = GCHandle.FromIntPtr(lParam);

            if (gcChildhandlesList == null || gcChildhandlesList.Target == null)
            {
                return false;
            }

            List<IntPtr> childHandles = gcChildhandlesList.Target as List<IntPtr>;
            childHandles.Add(hWnd);

            return true;
        }
    }


 void printWindows(IntPtr parent, int tabLevel)
        {
            var w = new WindowHandleInfo(parent);
            foreach (IntPtr h in w.GetAllChildHandles())
            {
                string caption = GetTextBoxText(h) ?? "not found";
                Debug.Write(new string('\t', tabLevel));
                Debug.WriteLine(caption);
                printWindows(h, tabLevel + 1);
            }
        }

 int GetTextBoxTextLength(IntPtr hTextBox)
        {
            // helper for GetTextBoxText
            const int WM_GETTEXTLENGTH = 0x000E;
            int result = SendMessage(hTextBox, WM_GETTEXTLENGTH, 0, IntPtr.Zero);
            return result;
        }

        string GetTextBoxText(IntPtr hTextBox)
        {
            const int WM_GETTEXT = 0x000D;
            int len = GetTextBoxTextLength(hTextBox);
            if (len <= 0) return null;  // no text
            StringBuilder sb = new StringBuilder(len + 1);
            SendMessage(hTextBox, WM_GETTEXT, len + 1, sb);
            return sb.ToString();
        }

using like this:

 IntPtr parent = FindWindow(IntPtr.Zero, "my app title");
 printWindows(parent, 0);

But I can't see anyhing related to Iniciar gravação button.

Answer 1

Qt UI controls (widgets, in Qt lexicon. Aka buttons, line edits, comboboxes, etc.) are not backed by native controls. They just steal the native UI look and feel from them and mimic it.

For this reason, you won't find those controls using some of those "spy" tools -- you may still find them through accessibility, though (*).

Or, you can inspect your application using other Qt-specific tools, such as GammaRay for debugging or Squish for UI testing.

(*) controls shipped with Qt are accessibile, but if someone manually reimplements something that looks like a button and doesn't provide it with accessibility then you can't do much about that.