I went ahead and tackled it this morning. As I suspected, it required a
nativeEvent() handler to achieve my desired effect. In the interests of
posterity, here's the Windows code that works for my context. It "glues" a
window directly onto the desktop, and keeps it from changing its Z-order when
the user tries to click on it with the mouse:
bool Headline::nativeEvent(const QByteArray &eventType, void *message, long
*result)
{
*result = 0L;
if(glue_to_desktop)
{
if(!QString(eventType).compare("windows_generic_MSG"))
{
MSG* msg = (MSG*)message;
if(msg->message == WM_WINDOWPOSCHANGING)
{
RECT r;
HWND bottom = nullptr;
// assume the first window consuming the entire virtual
// desktopsize IS the desktop (e.g., "Program Manager"),
// andglue ourselves right on top of it
int desktop_width = GetSystemMetrics(SM_CXVIRTUALSCREEN);
int desktop_height = GetSystemMetrics(SM_CYVIRTUALSCREEN);
HWND w = GetTopWindow(NULL);
while(w)
{
GetWindowRect(w, &r);
if((r.right - r.left) == desktop_width && (r.bottom -
r.top) == desktop_height)
break;
if(IsWindowVisible(w))
bottom = w;
w = GetNextWindow(w, GW_HWNDNEXT);
}
auto pwpos = (WINDOWPOS*)msg->lParam;
pwpos->hwndInsertAfter = bottom;
pwpos->flags &= (~SWP_NOZORDER);
// fall through to the return
}
}
}
return false;
}
On 12/5/2016 10:44 AM, Bob Hood wrote:
Ok, here's another one for the brain trust...
I'm creating windows in a tasktray application (Windows 7 64-bit). These
"child" windows inherit from QWidget and are not parented, but they are
being created by the main application.
I can "glue" them to the screen (i.e., top of Z order) using the
Qt::WindowStaysOnTopHint flag, and that works perfectly. However, I want to
"glue" them to the desktop instead (i.e., bottom of Z order), and using
Qt::WindowStaysOnBottomHint doesn't appear to accomplish that with the same
persistence as Qt::WindowStaysOnTopHint, at least under Windows.
I understand this may require a platform-specific solution, and I can accept
that since this tool will probably only be used under Windows. I even tried
using SetWindowPos() directly after opening the window:
void Headline::showEvent(QShowEvent *event)
{
QWidget::showEvent(event);
SetWindowPos((HWND)winId(), HWND_BOTTOM, 0, 0, 0, 0,
SWP_NOACTIVATE|SWP_NOMOVE|SWP_NOSIZE);
}
But that doesn't seem to maintain the order. I'm also using
Qt::WA_ShowWithoutActivating, and that seems to work, but once I move the
window (using QPropertyAnimation, for example), activation and Z-order
shifting become an issue. I guess my question becomes: Is there a way to
force a window to the background behind all other windows, and /keep/it
there even if it is being interacted with--programmatically or, for example,
by the user clicking on it? Something tells me that intercepting and
ignoring events might do it, but I'm not sure if that's the right approach.
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