MFC自定义控件焦点设置求助：Dialog中按钮无法释放焦点

Hey there, let's tackle this focus issue you're seeing in your Dialog-based custom CWnd control. The fact that it works fine in SDI but breaks in Dialog gives us a clue—Dialogs have their own focus management logic that's a bit different from SDI's document/view setup. Here are some targeted fixes to try:

• Handle WM_KILLFOCUS properly in your button controls
  If your buttons are part of the CWnd-derived class (either custom or standard CButton), make sure you're overriding OnKillFocus to update their visual state. When a button loses focus, set a boolean flag (like m_bHasFocus = false) and call InvalidateRect() to trigger a repaint. In your OnPaint method, check this flag to skip drawing the blue highlight when the button isn't focused.

• Ensure your Dialog uses the WS_EX_CONTROLPARENT extended style
  Dialogs depend on this style to manage smooth focus switching between child controls. You can enable it in two ways:

  1. In the resource editor, go to your Dialog's properties → Extended Styles → check "Control Parent".
  2. Programmatically add it in OnInitDialog with:

     ModifyStyleEx(0, WS_EX_CONTROLPARENT);
     

• Manually track and update focus in button click handlers
  Add a member variable to your CWnd-derived class (e.g., CButton* m_pCurrentFocusedBtn) to keep track of the button that's currently focused. When another button is clicked (handle the BN_CLICKED message):

  1. If m_pCurrentFocusedBtn isn't null, send it a WM_KILLFOCUS message and set its focus state to false.
  2. Call pClickedBtn->SetFocus() to give focus to the new button, then update m_pCurrentFocusedBtn to point to this new button.

• Don't block default focus handling in your CWnd class
  If you've overridden OnSetFocus or OnKillFocus in your CWnd-derived class, always make sure to call the base class implementation first. For example:

  void CMyCustomWnd::OnSetFocus(CWnd* pOldWnd)
  {
      CWnd::OnSetFocus(pOldWnd); // Let the base class handle standard focus logic
      // Your custom focus code here (if needed)
  }
  

  Skipping the base class call can disrupt the system's focus management, especially in Dialogs.

Give these steps a try—chances are one of them will resolve the stuck focus issue. The core problem here is that Dialogs have a more structured focus system compared to SDI, so you might need to explicitly handle transitions that happen automatically in the document/view framework.

内容的提问来源于stack exchange，提问作者심상원