diff --git a/abstract_client.h b/abstract_client.h
--- a/abstract_client.h
+++ b/abstract_client.h
@@ -647,8 +647,12 @@
      **/
     virtual void killWindow() = 0;
 
-    // TODO: remove boolean trap
-    static bool belongToSameApplication(const AbstractClient* c1, const AbstractClient* c2, bool active_hack = false);
+    enum class SameApplicationCheck {
+        RelaxedForActive = 1 << 0,
+        AllowCrossProcesses = 1 << 1
+    };
+    Q_DECLARE_FLAGS(SameApplicationChecks, SameApplicationCheck)
+    static bool belongToSameApplication(const AbstractClient* c1, const AbstractClient* c2, SameApplicationChecks checks = SameApplicationChecks());
 
     bool hasApplicationMenu() const;
     bool applicationMenuActive() const {
@@ -765,8 +769,7 @@
      * Default implementation does nothig.
      **/
     virtual void doMinimize();
-    // TODO: remove boolean trap
-    virtual bool belongsToSameApplication(const AbstractClient *other, bool active_hack) const = 0;
+    virtual bool belongsToSameApplication(const AbstractClient *other, SameApplicationChecks checks) const = 0;
 
     virtual void doSetSkipTaskbar();
     virtual void doSetSkipPager();
@@ -1155,5 +1158,6 @@
 
 Q_DECLARE_METATYPE(KWin::AbstractClient*)
 Q_DECLARE_METATYPE(QList<KWin::AbstractClient*>)
+Q_DECLARE_OPERATORS_FOR_FLAGS(KWin::AbstractClient::SameApplicationChecks)
 
 #endif
diff --git a/abstract_client.cpp b/abstract_client.cpp
--- a/abstract_client.cpp
+++ b/abstract_client.cpp
@@ -104,9 +104,9 @@
 {
 }
 
-bool AbstractClient::belongToSameApplication(const AbstractClient *c1, const AbstractClient *c2, bool active_hack)
+bool AbstractClient::belongToSameApplication(const AbstractClient *c1, const AbstractClient *c2, SameApplicationChecks checks)
 {
-    return c1->belongsToSameApplication(c2, active_hack);
+    return c1->belongsToSameApplication(c2, checks);
 }
 
 bool AbstractClient::isTransient() const
diff --git a/activation.cpp b/activation.cpp
--- a/activation.cpp
+++ b/activation.cpp
@@ -609,7 +609,7 @@
 
     // Unconditionally allow intra-client passing around for lower stealing protections
     // unless the active client has High interest
-    if (AbstractClient::belongToSameApplication(c, ac, true) && protection < FSP::High) {
+    if (AbstractClient::belongToSameApplication(c, ac, AbstractClient::SameApplicationCheck::RelaxedForActive) && protection < FSP::High) {
         qCDebug(KWIN_CORE) << "Activation: Belongs to active application";
         return true;
     }
@@ -659,7 +659,7 @@
         return true; // no active client -> always allow
     }
     // TODO window urgency  -> return true?
-    if (AbstractClient::belongToSameApplication(c, ac, true)) {
+    if (AbstractClient::belongToSameApplication(c, ac, AbstractClient::SameApplicationCheck::RelaxedForActive)) {
         qCDebug(KWIN_CORE) << "Raising: Belongs to active application";
         return true;
     }
@@ -753,13 +753,13 @@
         // from already running application if this application
         // is not the active one (unless focus stealing prevention is turned off).
         Client* act = dynamic_cast<Client*>(workspace()->mostRecentlyActivatedClient());
-        if (act != NULL && !belongToSameApplication(act, this, true)) {
+        if (act != NULL && !belongToSameApplication(act, this, SameApplicationCheck::RelaxedForActive)) {
             bool first_window = true;
             auto sameApplicationActiveHackPredicate = [this](const Client *cl) {
                 // ignore already existing splashes, toolbars, utilities and menus,
                 // as the app may show those before the main window
                 return !cl->isSplash() && !cl->isToolbar() && !cl->isUtility() && !cl->isMenu()
-                        && cl != this && Client::belongToSameApplication(cl, this, true);
+                        && cl != this && Client::belongToSameApplication(cl, this, SameApplicationCheck::RelaxedForActive);
             };
             if (isTransient()) {
                 auto clientMainClients = [this] () -> ClientList {
diff --git a/client.h b/client.h
--- a/client.h
+++ b/client.h
@@ -247,7 +247,7 @@
     /// Does 'delete c;'
     static void deleteClient(Client* c);
 
-    static bool belongToSameApplication(const Client* c1, const Client* c2, bool active_hack = false);
+    static bool belongToSameApplication(const Client* c1, const Client* c2, SameApplicationChecks checks = SameApplicationChecks());
     static bool sameAppWindowRoleMatch(const Client* c1, const Client* c2, bool active_hack);
 
     void killWindow() override;
@@ -377,7 +377,7 @@
 protected:
     virtual void debug(QDebug& stream) const;
     void addDamage(const QRegion &damage) override;
-    bool belongsToSameApplication(const AbstractClient *other, bool active_hack) const override;
+    bool belongsToSameApplication(const AbstractClient *other, SameApplicationChecks checks) const override;
     void doSetActive() override;
     void doSetKeepAbove() override;
     void doSetKeepBelow() override;
diff --git a/client.cpp b/client.cpp
--- a/client.cpp
+++ b/client.cpp
@@ -2110,13 +2110,13 @@
     Toplevel::addDamage(damage);
 }
 
-bool Client::belongsToSameApplication(const AbstractClient *other, bool active_hack) const
+bool Client::belongsToSameApplication(const AbstractClient *other, SameApplicationChecks checks) const
 {
     const Client *c2 = dynamic_cast<const Client*>(other);
     if (!c2) {
         return false;
     }
-    return Client::belongToSameApplication(this, c2, active_hack);
+    return Client::belongToSameApplication(this, c2, checks);
 }
 
 void Client::updateTabGroupStates(TabGroup::States states)
diff --git a/group.cpp b/group.cpp
--- a/group.cpp
+++ b/group.cpp
@@ -419,7 +419,7 @@
 // Client
 //****************************************
 
-bool Client::belongToSameApplication(const Client* c1, const Client* c2, bool active_hack)
+bool Client::belongToSameApplication(const Client* c1, const Client* c2, SameApplicationChecks checks)
 {
     bool same_app = false;
 
@@ -438,16 +438,18 @@
         same_app = true; // same client leader
 
     // tests that mean they most probably don't belong together
-    else if (c1->pid() != c2->pid()
+    else if ((c1->pid() != c2->pid() && !checks.testFlag(SameApplicationCheck::AllowCrossProcesses))
             || c1->wmClientMachine(false) != c2->wmClientMachine(false))
         ; // different processes
     else if (c1->wmClientLeader() != c2->wmClientLeader()
             && c1->wmClientLeader() != c1->window() // if WM_CLIENT_LEADER is not set, it returns window(),
-            && c2->wmClientLeader() != c2->window()) // don't use in this test then
+            && c2->wmClientLeader() != c2->window() // don't use in this test then
+            && !checks.testFlag(SameApplicationCheck::AllowCrossProcesses))
         ; // different client leader
     else if (!resourceMatch(c1, c2))
         ; // different apps
-    else if (!sameAppWindowRoleMatch(c1, c2, active_hack))
+    else if (!sameAppWindowRoleMatch(c1, c2, checks.testFlag(SameApplicationCheck::RelaxedForActive))
+            && !checks.testFlag(SameApplicationCheck::AllowCrossProcesses))
         ; // "different" apps
     else if (c1->pid() == 0 || c2->pid() == 0)
         ; // old apps that don't have _NET_WM_PID, consider them different
diff --git a/shell_client.h b/shell_client.h
--- a/shell_client.h
+++ b/shell_client.h
@@ -156,7 +156,7 @@
 
 protected:
     void addDamage(const QRegion &damage) override;
-    bool belongsToSameApplication(const AbstractClient *other, bool active_hack) const override;
+    bool belongsToSameApplication(const AbstractClient *other, SameApplicationChecks checks) const override;
     void doSetActive() override;
     Layer layerForDock() const override;
     void changeMaximize(bool horizontal, bool vertical, bool adjust) override;
diff --git a/shell_client.cpp b/shell_client.cpp
--- a/shell_client.cpp
+++ b/shell_client.cpp
@@ -553,9 +553,13 @@
     return QByteArray();
 }
 
-bool ShellClient::belongsToSameApplication(const AbstractClient *other, bool active_hack) const
+bool ShellClient::belongsToSameApplication(const AbstractClient *other, SameApplicationChecks checks) const
 {
-    Q_UNUSED(active_hack)
+    if (checks.testFlag(SameApplicationCheck::AllowCrossProcesses)) {
+        if (other->desktopFileName() == desktopFileName()) {
+            return true;
+        }
+    }
     if (auto s = other->surface()) {
         return s->client() == surface()->client();
     }
@@ -854,7 +858,7 @@
         // check that it doesn't belong to the desktop
         const auto &clients = waylandServer()->clients();
         for (auto c: clients) {
-            if (!belongsToSameApplication(c, false)) {
+            if (!belongsToSameApplication(c, SameApplicationChecks())) {
                 continue;
             }
             if (c->isDesktop()) {
diff --git a/tabbox/tabbox.cpp b/tabbox/tabbox.cpp
--- a/tabbox/tabbox.cpp
+++ b/tabbox/tabbox.cpp
@@ -200,7 +200,7 @@
                 continue;
             }
             if ((c = dynamic_cast< TabBoxClientImpl* >(client.data()))) {
-                if (AbstractClient::belongToSameApplication(c->client(), current)) {
+                if (AbstractClient::belongToSameApplication(c->client(), current, AbstractClient::SameApplicationCheck::AllowCrossProcesses)) {
                     return false;
                 }
             }
@@ -212,7 +212,7 @@
             return false;
         }
         if ((c = dynamic_cast< TabBoxClientImpl* >(pointer.data()))) {
-            if (AbstractClient::belongToSameApplication(c->client(), current)) {
+            if (AbstractClient::belongToSameApplication(c->client(), current, AbstractClient::SameApplicationCheck::AllowCrossProcesses)) {
                 return true;
             }
         }