hwndParent<\/code>),\nbut the caption buttons still worked, as did many of the other\ncontrols on the window.\n<\/p>\n\nIn the second case,\ndisabling the wrong window created a different problem:\nWhen the modal UI was complete,\nthe window manager activated the top-level window that was the\nowner of the modal window since that window was never disabled.\nThis caused the top-level window to receive a WM_ACTIVATE<\/code>\nmessage,\nwhich it handled by putting focus on the control that had focus\nwhen the top-level window was deactivated.\nUnfortunately, that window was the window that was passed\nas the hwndParent<\/code>,\nwhich was disabled by mistake<\/i>.\nThe attempt to restore focus failed,\nand when the manual modal UI finally finished up and enabled\nthe child window, it was too late.\nYou wound up with focus nowhere and a dead keyboard.\nThis second problem was\nreported as simply “SetFocus<\/code> is not working.”\nOnly after peeling back a few layers (and application of some\npsychic powers) did the root cause emerge.\n<\/p>\n\nNow, even though this was a subtle problem,\nyou already knew all the pieces that went into it since I had\ncovered them earlier.\nAnd as for those psychic powers that I used?\nIt’s really not that magic.\nIn this case of psychic debugging, I worked backwards.\nIn response to the report that\nSetFocus<\/code> was not working,\nthe next set of questions was to determine why.\nIs it a valid window handle?\nDoes the window belong to your thread?\nIs it enabled?\n<\/p>\n\nAha, the window isn’t enabled.\nThat’s when the customer also mentioned that they were doing\nthis inside a WM_ACTIVATE<\/code> handler.\nIf you’re gaining activation, who were you gaining it from?\nOh, a modal dialog, you say?\nOne that you’re managing manually?\nOnce I discovered that they were trying to manage modal UI manually,\nI suspected that they were disabling the wrong window,\nsince that fit all the symptoms and it’s something that people tend\nto get wrong.\n<\/p>\n\nMost of what looks like psychic debugging is really just\nknowing what people tend to get wrong.<\/p>\n","protected":false},"excerpt":{"rendered":"
Some time ago, I was asked to look at two independent problems with people trying to do modal UI manually. Well, actually, when the issues were presented to me, they weren’t described in quite that way. They were more along the lines of, “Something strange is happening in our UI. Can you help?” Only in […]<\/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-29143","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-code"],"acf":[],"blog_post_summary":"
Some time ago, I was asked to look at two independent problems with people trying to do modal UI manually. Well, actually, when the issues were presented to me, they weren’t described in quite that way. They were more along the lines of, “Something strange is happening in our UI. Can you help?” Only in […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/29143","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=29143"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/29143\/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=29143"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=29143"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=29143"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}