问题
I have some legacy code and for some reason, menu items are being enabled or disabled on launch. My question is, how? Is there any way to do this without calling the EnableMenuItem() function? Is there a way for MFC to do the opposite from what the resource settings say?
I'm also at a loss as to why the current ones are being disabled or reenabled in a SDI when the last child window has closed. This is probably due to me not understanding the framework well enough and I thought I've read through all of the docs here.
回答1:
With MFC, menu items could be disabled if there is neither a ON_UPDATE_COMMAND_UI handler nor a ON_COMMAND handler for the menu item -- according to this MSDN article,
If the framework does not find an ON_UPDATE_COMMAND_UI entry during command routing, it automatically enables the user-interface object if there is an ON_COMMAND entry somewhere with the same command ID. Otherwise, it disables the user-interface object ... It is possible to disable the default disabling of user-interface objects. For more information, see the m_bAutoMenuEnable member of class CFrameWnd in the MFC Reference
[this applies to menu-items and toolbar-items]
来源：https://stackoverflow.com/questions/25508413/menu-items-are-being-enabled-or-disabled-by-default-why