maximizing the panel actually works

src/shell/panelview.cpp

@@ -126,6 +126,19 @@ KConfigGroup PanelView::config() const
     }
 }
 
+void PanelView::maximize()
+{
+    int length;
+    if (containment()->formFactor() == Plasma::Types::Vertical) {
+        length = screen()->size().height();
+    } else {
+        length = screen()->size().width();
+    }
+    setOffset(0);
+    setMinimumLength(length);
+    setMaximumLength(length);
+}
+
 Qt::Alignment PanelView::alignment() const
 {
     return m_alignment;

src/shell/panelview.h

@@ -54,6 +54,8 @@ public:
 
     virtual KConfigGroup config() const;
 
+    Q_INVOKABLE void maximize();
+
     Qt::Alignment alignment() const;
     void setAlignment(Qt::Alignment alignment);