How can I inform the OS to position the Cloud Clipboard (or Emoji Panel) over my window?

I have a traditional Win32 C++-based Windows desktop application. In the window, I handle <kbd>Ctrl+V</kbd> to process pasted content. The same window also handles keystrokes with the typed character added to the content I manage. All this works fine!

However, if the user presses <kbd>Win+V</kbd> to paste from the Cloud Clipboard, or presses <kbd>Win+.</kbd> to type using the Emoji panel, those popup windows are not positioned anywhere near my window, even though it is the active window with input focus.

Is there an API I should call, or a Windows message I need to be responding to, in order to inform the OS that my window wants the panel opened nearby, preferably along its border, or a rect I supply?

I have tried calling SetCaretPos(), but the behavior doesn't affect anything. I see APIs all around being a Clipboard Viewer, but that's for windows which want to watch for clipboard content changes, and not a normal window accepting input like mine.

I just want the OS popup to be near to my window, as happens for the common Edit or Combo controls when they have input focus.

Some screenshots to illustrate:

Desired Location ala the Run dialog:

Bug replicated with a MFC test program:

To replicate the bug yourself, create an MFC app supporting the standard Edit > Paste menu item with the ID_EDIT_PASTE accelerator. Map that to an OnEditPaste handler like below (just shows any CF_TEXT in a MessageBox):

void TestView::OnEditPaste()
{
	if (OpenClipboard()) {
		if (auto hText = ::GetClipboardData(CF_TEXT); hText != NULL) {
			if (auto pData = ::GlobalLock(hText); pData) {
				std::string msg{(char*)pData, ::GlobalSize(hText)};
				::MessageBoxA(GetSafeHwnd(), msg.c_str(), "Pasted", MB_OK);
				::GlobalUnlock(hText);
			}
		}
		CloseClipboard();
	}
}

Run your app and activate the view. Then press <kbd>Win+V</kbd> and the Cloud Clipboard opens far away; that's the issue I'm desperate to solve.

I found a similar situation here: How to set Emoji popup position in Win32

That question is regarding the Emoji panel but the fix also affects the Cloud Clipboard location as well. It seems that the OS treats both as special IME windows.

The key is to respond to the WM_IME_REQUEST message, specifically, the IMR_QUERYCHARPOSITION query.

If you're using MFC, you'll want something like this. This just places the prompt in the top-left of the window but you should get the idea.

class TestView : public CView
{
    . . .
    afx_msg LRESULT OnImeRequest(WPARAM wParam, LPARAM lParam);
}

BEGIN_MESSAGE_MAP(TestView, CView)
    . . .
	ON_MESSAGE(WM_IME_REQUEST, OnImeRequest)
END_MESSAGE_MAP()

LRESULT TestView::OnImeRequest(WPARAM wParam, LPARAM lParam)
{
	switch (wParam) {
		case IMR_QUERYCHARPOSITION: {
			RECT rcWindow{};
			GetWindowRect(&rcWindow);

			IMECHARPOSITION* charPos = (IMECHARPOSITION*)lParam;
			charPos->dwSize = sizeof(IMECHARPOSITION);
			charPos->pt.x = rcWindow.left;
			charPos->pt.y = rcWindow.top;
			charPos->cLineHeight = 10;
			GetClientRect(&charPos->rcDocument);
			return 1;
		}
	}

	return 0;
}