effects/windowview: always set the mode when activating with gestures

Otherwise the mode uses is defined by the last time the effect was used and
thus not very predictable

src/effects/windowview/windowvieweffect.cpp

@@ -115,6 +115,7 @@ WindowViewEffect::WindowViewEffect()
             switch (m_status) {
             case Status::Inactive:
             case Status::Activating:
+                setMode(ModeAllDesktops);
                 partialActivate(progress);
                 break;
             case Status::Active: