Using AlwaysActivateWindow to gain foreground in WIN10 using QT6.2

supa5000

Dear all,

The background:

Our application is "single instance" type of application, that during startups checks if another instance is running
We have custom files assosiated with our application
When user clicks on file explorer our file, the windows launches our application
If there is another instance running, it will just send the filenames and the "old" instance opens up the file

Now on the last bullet, i would really much like to get the "old" main-window to foreground. Like i think most of windows software does.

No what i have

        win->show();
        win->raise();
        win->requestActivate();

Only makes the window to "blink" on taskbar if the window is open, but on background.

During my googling i found out apparantly there is https://doc.qt.io/qt-5/qwindowswindowfunctions.html - but these are not available at 6?

When looking at the source code, i did find some references that the functinality would be there https://code.qt.io/cgit/qt/qtbase.git/tree/src/plugins/platforms/windows/qwindowswindow.cpp?h=6.2.2#n2625 - but how should this be used?

Br,
Pauli

Bonnie

As I tested, to get the equivalent effect of qt5 version's

QWindowsWindowFunctions::setWindowActivationBehavior(QWindowsWindowFunctions::AlwaysActivateWindow)

in qt6, you'll first need to add this in your .pro file

QT += gui-private

Then in you source code

#include <private/qguiapplication_p.h>

...

if(auto inf = qApp->nativeInterface<QNativeInterface::Private::QWindowsApplication>()) {
    inf->setWindowActivationBehavior(QNativeInterface::Private::QWindowsApplication::AlwaysActivateWindow);
}

supa5000

Thanks @Bonnie ! It worked out of the box.

Only thing i needed (for the record, if fellow googlers end up here) as i use CMake based build system was to add

include_directories(${Qt6Gui_PRIVATE_INCLUDE_DIRS})

And due compiling flags (warnings as errors):

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wpedantic"
#include <private/qguiapplication_p.h>
#pragma GCC diagnostic pop

Again for the record, the warning - suppressed by the above - was:

In file included from C:/QT/6.3.0/mingw_64/include/QtCore/6.3.0/QtCore/private/qobject_p.h:64,
                 from C:/QT/6.3.0/mingw_64/include/QtCore/6.3.0/QtCore/private/qcoreapplication_p.h:63,
                 from C:/QT/6.3.0/mingw_64/include/QtGui/6.3.0/QtGui/private/qguiapplication_p.h:59,
                 from C:/msys64/home/salmenrinne/pxr-studio/src/main/main.cpp:188:
C:/QT/6.3.0/mingw_64/include/QtCore/6.3.0/QtCore/private/qproperty_p.h:263:16: error: ISO C++ prohibits anonymous structs [-Wpedantic]
  263 |         struct {
      |                ^