Navigating a dialog with embedded children dialog

@ChuckieAJ You'll also want to make sure that there isn't a duplication of control ids between the top level dialog and the child dialog.

@David Lowndes, Your guidance seems like it should be an Answer, not a comment. :)

@David Lowndes

Thanks for the heads up. I did need to switch that in my parent:

I can now confirm that it is correctly tabbing through all controls:

But, this raises a related problem. Normal mode is fine, but when I use my custom dark mode:

See? In dark mode my radio / check box controls are not drawing a focus rectangle around the focused control.

I am using custom draw for those controls:

#pragma warning(disable: 26429)
	bool CDarkModeBase::OnNotify(
		_In_ const CWnd* pParentWnd, 
		_In_ LPARAM lParam, 
		_Outptr_ LRESULT* pResult, 
		_In_ bool isChildDialog /*= false*/)
	{
		if (!DarkModeTools::InvokeUseDarkModeFunction())
			return false;
	
		NMHDR* pNMHDR = reinterpret_cast<NMHDR*>(lParam);
		if (pNMHDR->code == NM_CUSTOMDRAW)
		{
			LPNMCUSTOMDRAW pNMCD = reinterpret_cast<LPNMCUSTOMDRAW>(pNMHDR);
			*pResult = CDRF_DODEFAULT;

			if (pNMCD->dwDrawStage == CDDS_PREPAINT)
			{
				if (!pParentWnd)
					return false;

#pragma warning(disable: 26462 26472)
				const auto pControl = pParentWnd->GetDlgItem(static_cast<int>(pNMHDR->idFrom));
				if (pControl)
				{
					CString className;
					GetClassName(pControl->GetSafeHwnd(), className.GetBuffer(256), 256);
					className.ReleaseBuffer();

					if (className == L"Button")
					{
						const CButton* pButton = reinterpret_cast<CButton*>(pControl);
						if (pButton)
						{
							const auto buttonStyle = pButton->GetStyle();
							if ((buttonStyle & BS_CHECKBOX) == BS_CHECKBOX ||
								(buttonStyle & BS_AUTOCHECKBOX) == BS_AUTOCHECKBOX ||
								(buttonStyle & BS_RADIOBUTTON) == BS_RADIOBUTTON ||
								(buttonStyle & BS_AUTORADIOBUTTON) == BS_AUTORADIOBUTTON)
							{
								const bool isAlignedTop = (buttonStyle & BS_TOP) == BS_TOP;
								const bool  isAlignedVCenter = (buttonStyle & BS_VCENTER) == BS_VCENTER;
								const bool isAlignedBottom = (buttonStyle & BS_BOTTOM) == BS_BOTTOM;
								const bool isAlignedLeft = (buttonStyle & BS_LEFT) == BS_LEFT;
								const bool isAlignedRight = (buttonStyle & BS_RIGHT) == BS_RIGHT;
								const bool isLeftText = (buttonStyle & BS_LEFTTEXT) == BS_LEFTTEXT;

								CDC* pDC = CDC::FromHandle(pNMCD->hdc);
								if (pDC)
								{
									// Save original text color and background mode
									const auto oldBkMode = pDC->SetBkMode(TRANSPARENT);
									const auto oldTextColor = pDC->GetTextColor();

									// Set text color based on control state
									if (!pControl->IsWindowEnabled())
									{
										pDC->SetTextColor(GetSysColor(COLOR_GRAYTEXT));
									}
									else
									{
										pDC->SetTextColor(DarkModeTools::kDarkTextColor);
									}

									// Get checkbox size
									CSize sizeCheckBox(16, 16); // Default size
									HTHEME hTheme = OpenThemeData(nullptr, L"Button");
									if (hTheme)
									{
										GetThemePartSize(hTheme, pNMCD->hdc,
											BP_CHECKBOX, CBS_UNCHECKEDNORMAL, nullptr, TS_DRAW, &sizeCheckBox);
										CloseThemeData(hTheme);
									}

									// Compute horizontal shift
									CSize sizeExtent;
									GetTextExtentPoint32(pNMCD->hdc, L"0", 1, &sizeExtent);
									const int nShift = sizeExtent.cx / 2;

									// Adjust text rectangle
									CRect rc(pNMCD->rc);

									if (isLeftText)
									{
										// Shift text to the left of the checkbox
										rc.right -= (sizeCheckBox.cx + nShift);
									}
									else if (isAlignedRight)
									{
										// Subtract checkbox width from the right edge
										rc.right -= sizeCheckBox.cx + nShift;
									}
									else
									{
										// Add checkbox width to the left edge (default behavior)
										rc.OffsetRect(sizeCheckBox.cx + nShift, 0);
									}

									// Get text
									CString strText;
									pControl->GetWindowText(strText);

									// Measure text height
									CRect rcMeasure(rc);
									pDC->DrawText(strText, &rcMeasure, DT_LEFT | DT_WORDBREAK | DT_EDITCONTROL | DT_CALCRECT);

									// Center text vertically based on alignment
									const auto textHeight = rcMeasure.Height();
									int verticalOffset = 0;  // Default to no offset

									if (isAlignedTop)
									{
										verticalOffset = 0; // No adjustment needed
									}
									else if (isAlignedBottom)
									{
										verticalOffset = rc.Height() - textHeight;
									}
									else
									{
										verticalOffset = (rc.Height() - textHeight) / 2;
									}

									rc.top += verticalOffset;
									rc.bottom = rc.top + textHeight;

									// Draw text with appropriate alignment
									UINT textFormat = DT_WORDBREAK | DT_EDITCONTROL | DT_EXPANDTABS | DT_END_ELLIPSIS;
									if (isAlignedRight)
									{
										textFormat |= DT_RIGHT; // Align text to the right
									}
									else
									{
										textFormat |= DT_LEFT; // Align text to the left
									}

									// Draw text
									pDC->DrawText(strText, &rc, textFormat);

									// Restore original properties
									pDC->SetBkMode(oldBkMode);
									pDC->SetTextColor(oldTextColor);

									*pResult = CDRF_SKIPDEFAULT;
									return true;
								}
							}
						}
					}
					else if (className == L"msctls_trackbar32")
					{
						// Request notifications for individual items.
						*pResult = CDRF_NOTIFYITEMDRAW;
						return true;
					}
				}
			}
			else if (pNMCD->dwDrawStage == CDDS_ITEMPREPAINT)
			{
				// Check if the item is the channel area.
				if (pNMCD->dwItemSpec == TBCD_CHANNEL)
				{
					// Set the background color.
					HBRUSH hBrush = CreateSolidBrush(DarkModeTools::kDarkSliderChannelColor);
					FillRect(pNMCD->hdc, &pNMCD->rc, hBrush);
					DeleteObject(hBrush);

					// Return CDRF_SKIPDEFAULT to prevent default drawing.
					*pResult = CDRF_SKIPDEFAULT;
					return true;
				}
			}
		}
		return false;
	}

My code needs tweaking to draw the focus rect around the focused radio / check box.

Maybe check the state of the controls and draw the focus rectangle yourself when needed.