在后台进程中，我想在托盘区域显示像气球一样的短消息。但是，我不想为此添加托盘图标。因此，我创建了一个工具提示图标并希望将其放置在托盘附近。但是，发送TTM_UPDATETIPTEXT, TTM_TRACKPOSITION,TTM_TRACKACTIVATE返回 0。虽然我不确定这是否应该是这种情况，但以下代码没有显示工具提示窗口，我不知道为什么：
这是代码：
// "hwnd" is the HWND to the hidden background window of my background process
HWND hTrayWnd = FindWindow(_T("Shell_TrayWnd"), NULL);
GetWindowRect(hTrayWnd, &trayPos);
HWND hwndTip = CreateWindowEx(NULL, TOOLTIPS_CLASS, NULL,
WS_POPUP | TTS_ALWAYSTIP | TTS_BALLOON,
CW_USEDEFAULT, CW_USEDEFAULT,
CW_USEDEFAULT, CW_USEDEFAULT,
hWnd, NULL, NULL, NULL);
LRESULT ret;
TOOLINFO toolInfo = { 0 };
ZeroMemory(&toolInfo, sizeof(toolInfo));
toolInfo.cbSize = sizeof(toolInfo);
toolInfo.hinst = GetModuleHandle(NULL);
toolInfo.lpszText = _T("Test Test");
toolInfo.hwnd = hWnd;
ret = SendMessage(hwndTip, TTM_SETTITLE, TTI_INFO , (LPARAM)_T("Test Title"));
此调用返回零：
ret = SendMessage(hwndTip, TTM_UPDATETIPTEXT, 0 , (LPARAM)&toolInfo); // needs hinst, lpszText, hwnd, cbSize
此调用也返回零：
ret = SendMessage(hwndTip, TTM_TRACKPOSITION, 0, MAKELPARAM(trayPos.left, trayPos.top));
ZeroMemory(&toolInfo, sizeof(toolInfo));
toolInfo.cbSize = sizeof(toolInfo);
toolInfo.hwnd = hWnd;
toolInfo.uId = 1;
这也是：
ret = SendMessage(hwndTip, TTM_TRACKACTIVATE, TRUE, (LPARAM)&toolInfo); // needs hwnd, uId, cbSize
并且永远不会显示工具提示窗口。
我还尝试使用TTM_ADDTOOL（如评论中所建议的）广告不同的SendMessage调用顺序，但这也返回零并且不显示工具提示：
LRESULT ret;
TOOLINFO toolInfo = { 0 };
ZeroMemory(&toolInfo, sizeof(toolInfo));
toolInfo.cbSize = sizeof(toolInfo);
toolInfo.lpszText = _T("Test Test");
toolInfo.hwnd = hWnd;
toolInfo.uId = 1;
toolInfo.rect.bottom = trayPos.bottom;
toolInfo.rect.left = trayPos.left;
toolInfo.rect.right = trayPos.right;
toolInfo.rect.top = trayPos.top;
//ret = SendMessage(hwndTip, TTM_ADDTOOL, 0, (LPARAM)&toolInfo);
ret = SendMessage(hwndTip, TTM_SETTITLE, TTI_INFO , (LPARAM)_T("Test Title"));
//ret = SendMessage(hwndTip, TTM_UPDATETIPTEXT, 0 , (LPARAM)&toolInfo); // needs hinst, lpszText, hwnd, uId, cbSize
//ret = SendMessage(hwndTip, TTM_TRACKPOSITION, 0, MAKELPARAM(trayPos.left, trayPos.top));
//ret = SendMessage(hwndTip, TTM_TRACKACTIVATE, TRUE, (LPARAM)&toolInfo); // needs hwnd, uId, cbSize
ret = SendMessage(hwndTip, TTM_ADDTOOL, 0, (LPARAM)&toolInfo);