SC_CLOSE<\/code> menu item\nin your system menu.\n<\/p>\n\nvoid DisableCloseButton(HWND hwnd)\n{\n EnableMenuItem(GetSystemMenu(hwnd, FALSE), SC_CLOSE,\n MF_BYCOMMAND | MF_DISABLED | MF_GRAYED);\n}\nvoid EnableCloseButton(HWND hwnd)\n{\n EnableMenuItem(GetSystemMenu(hwnd, FALSE), SC_CLOSE,\n MF_BYCOMMAND | MF_ENABLED);\n}\n<\/pre>\n\nThe other two caption buttons are controlled by window styles:\n<\/p>\n
\nvoid DisableMinimizeButton(HWND hwnd)\n{\n SetWindowLong(hwnd, GWL_STYLE,\n GetWindowLong(hwnd, GWL_STYLE) & ~WS_MINIMIZEBOX);\n}\nvoid EnableMinimizeButton(HWND hwnd)\n{\n SetWindowLong(hwnd, GWL_STYLE,\n GetWindowLong(hwnd, GWL_STYLE) | WS_MINIMIZEBOX);\n}\nvoid DisableMaximizeButton(HWND hwnd)\n{\n SetWindowLong(hwnd, GWL_STYLE,\n GetWindowLong(hwnd, GWL_STYLE) & ~WS_MAXIMIZEBOX);\n}\nvoid EnableMaximizeButton(HWND hwnd)\n{\n SetWindowLong(hwnd, GWL_STYLE,\n GetWindowLong(hwnd, GWL_STYLE) | WS_MAXIMIZEBOX);\n}\n<\/pre>\n\nWhy is the close button managed differently from the minimize\nand maximize buttons?\n<\/p>\n
\nHistory.\n<\/p>\n
\nOriginally, the window caption had only two buttons in the upper\nright corner, the minimize and maximize buttons,\nand they were controlled with a window style.\nWindows 95 added the Close button,\nbut then there was the question of knowing when to enable and disable it.\nBut wait, we already know when to enable and disable it:\nThe application told us when it enabled and disabled the\nSC_CLOSE<\/code> menu item.\nBingo, just hook up the Close button to the existing menu item\n(which applications were already in the habit of maintaining),\nand magic,\nit just works.\nNo need for applications to write special code to support the Close\nbutton.\nThey already wrote the code; they just didn’t realize it!\n<\/p>\n\nExercise<\/b>:\nWhat’s wrong with these alternative functions for enabling\nand disabling the Close button:\n<\/p>\n\n\/\/ code in italics is wrong\nvoid DisableCloseButton(HWND hwnd)\n{\n SetClassLong(hwnd, GCL_STYLE,\n GetClassLong(hwnd, GCL_STYLE) | CS_NOCLOSE);\n}\nvoid EnableCloseButton(HWND hwnd)\n{\n SetClassLong(hwnd, GCL_STYLE,\n GetClassLong(hwnd, GCL_STYLE) & ~CS_NOCLOSE);\n}<\/i>\n<\/pre>\n","protected":false},"excerpt":{"rendered":"A customer was having problems with the small icon that appears in the upper left corner of the caption: In my program, I need to enable and disable the Close button programmatically, since the program sometimes goes into a state where I don’t want the user to close it. I do this by removing the […]<\/p>\n","protected":false},"author":1069,"featured_media":111744,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[25],"class_list":["post-13803","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-code"],"acf":[],"blog_post_summary":"
A customer was having problems with the small icon that appears in the upper left corner of the caption: In my program, I need to enable and disable the Close button programmatically, since the program sometimes goes into a state where I don’t want the user to close it. I do this by removing the […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/13803","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/users\/1069"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/comments?post=13803"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/13803\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media\/111744"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media?parent=13803"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=13803"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=13803"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}