| MC_MTHITTESTINFO | Structure for message MC_MTM_HITTEST |
| MC_MTITEMA | Structure for manipulating with the tab item (ANSI variant) |
| MC_MTITEMW | Structure for manipulating with the tab item (unicode variant) |
| MC_MTITEMWIDTH | Structure for messages MC_MTM_SETITEMWIDTH and MC_MTM_GETITEMWIDTH |
| MC_NMBCDROPDOWN | Structure for notification MC_BCN_DROPDOWN |
| MC_NMHTMLURLA | Structure used for some HTML control notifications (ANSI variant) |
| MC_NMHTMLURLW | Structure used for some HTML control notifications (unicode variant) |
| MC_NMMTCLOSEITEM | Structure for notification MC_MTN_CLOSEITEM |
| MC_NMMTDELETEITEM | Structure for notification MC_MTN_DELETEITEM |
| MC_NMMTSELCHANGE | Structure for notification MC_MTN_SELCHANGE |
| MC_VERSION | Structure describing MCTRL.DLL version |