diff --git a/abstract_client.cpp b/abstract_client.cpp
index f125ec7262..c44f0b0deb 100644
--- a/abstract_client.cpp
+++ b/abstract_client.cpp
@@ -3116,4 +3116,50 @@ QSize AbstractClient::adjustedSize() const
     return sizeForClientSize(clientSize());
 }
 
+/**
+ * Returns @c true if the AbstractClient can be shown in full screen mode; otherwise @c false.
+ *
+ * Default implementation returns @c false.
+ */
+bool AbstractClient::isFullScreenable() const
+{
+    return false;
+}
+
+/**
+ * Returns @c true if the AbstractClient is currently being shown in full screen mode; otherwise @c false.
+ *
+ * A client in full screen mode occupies the entire screen with no window frame around it.
+ *
+ * Default implementation returns @c false.
+ */
+bool AbstractClient::isFullScreen() const
+{
+    return false;
+}
+
+/**
+ * Returns whether requests initiated by the user to enter or leave full screen mode are honored.
+ *
+ * Default implementation returns @c false.
+ */
+bool AbstractClient::userCanSetFullScreen() const
+{
+    return false;
+}
+
+/**
+ * Asks the AbstractClient to enter or leave full screen mode.
+ *
+ * Default implementation does nothing.
+ *
+ * @param set @c true if the AbstractClient has to be shown in full screen mode, otherwise @c false
+ * @param user @c true if the request is initiated by the user, otherwise @c false
+ */
+void AbstractClient::setFullScreen(bool set, bool user)
+{
+    Q_UNUSED(set)
+    Q_UNUSED(user)
+}
+
 }
diff --git a/abstract_client.h b/abstract_client.h
index 8bdfe35e03..ee32246f65 100644
--- a/abstract_client.h
+++ b/abstract_client.h
@@ -416,8 +416,8 @@ public:
     virtual bool isHiddenInternal() const = 0;
     // TODO: remove boolean trap
     virtual void hideClient(bool hide) = 0;
-    virtual bool isFullScreenable() const = 0;
-    virtual bool isFullScreen() const = 0;
+    virtual bool isFullScreenable() const;
+    virtual bool isFullScreen() const;
     // TODO: remove boolean trap
     virtual AbstractClient *findModal(bool allow_itself = false) = 0;
     virtual bool isTransient() const;
@@ -484,7 +484,7 @@ public:
     bool isMinimized() const {
         return m_minimized;
     }
-    virtual void setFullScreen(bool set, bool user = true) = 0;
+    virtual void setFullScreen(bool set, bool user = true);
 
     virtual void setClientShown(bool shown);
 
@@ -546,7 +546,7 @@ public:
     virtual bool isMaximizable() const = 0;
     virtual bool isMinimizable() const = 0;
     virtual QRect iconGeometry() const;
-    virtual bool userCanSetFullScreen() const = 0;
+    virtual bool userCanSetFullScreen() const;
     virtual bool userCanSetNoBorder() const = 0;
     virtual void checkNoBorder();
     virtual void setOnActivities(QStringList newActivitiesList);
diff --git a/internal_client.cpp b/internal_client.cpp
index 76b45f5730..06015c5f34 100644
--- a/internal_client.cpp
+++ b/internal_client.cpp
@@ -208,16 +208,6 @@ bool InternalClient::isCloseable() const
     return true;
 }
 
-bool InternalClient::isFullScreenable() const
-{
-    return false;
-}
-
-bool InternalClient::isFullScreen() const
-{
-    return false;
-}
-
 bool InternalClient::isMaximizable() const
 {
     return false;
@@ -397,17 +387,6 @@ void InternalClient::takeFocus()
 {
 }
 
-bool InternalClient::userCanSetFullScreen() const
-{
-    return false;
-}
-
-void InternalClient::setFullScreen(bool set, bool user)
-{
-    Q_UNUSED(set)
-    Q_UNUSED(user)
-}
-
 void InternalClient::setNoBorder(bool set)
 {
     if (!userCanSetNoBorder()) {
diff --git a/internal_client.h b/internal_client.h
index 140e87d69f..57204a846b 100644
--- a/internal_client.h
+++ b/internal_client.h
@@ -53,8 +53,6 @@ public:
     QByteArray windowRole() const override;
     void closeWindow() override;
     bool isCloseable() const override;
-    bool isFullScreenable() const override;
-    bool isFullScreen() const override;
     bool isMaximizable() const override;
     bool isMinimizable() const override;
     bool isMovable() const override;
@@ -82,8 +80,6 @@ public:
     AbstractClient *findModal(bool allow_itself = false) override;
     void setOnAllActivities(bool set) override;
     void takeFocus() override;
-    bool userCanSetFullScreen() const override;
-    void setFullScreen(bool set, bool user = true) override;
     void setNoBorder(bool set) override;
     void updateDecoration(bool check_workspace_pos, bool force = false) override;
     void updateColorScheme() override;