inputmethod: do not cover panels with the input method (e.g. virtual keyboard)

This way we can adapt the panels themselves to show useful UX like
hiding the keyboard or switching.

src/inputpanelv1client.cpp

@@ -69,9 +69,9 @@ void KWin::InputPanelV1Client::reposition()
                     return;
                 }
 
-                const auto outputGeometry = m_output->geometry();
-                QRect geo(outputGeometry.topLeft(), panelSize);
-                geo.translate((outputGeometry.width() - panelSize.width())/2, outputGeometry.height() - panelSize.height());
+                const QRect availableArea = workspace()->clientArea(MaximizeArea, m_output, desktop());
+                QRect geo(availableArea.topLeft(), panelSize);
+                geo.translate((availableArea.width() - panelSize.width())/2, availableArea.height() - panelSize.height());
                 updateGeometry(geo);
             }
         }   break;

src/workspace.cpp

@@ -2299,6 +2299,10 @@ QRect Workspace::clientArea(clientAreaOption opt, int screen, int desktop) const
     abort();
 }
 
+QRect Workspace::clientArea(clientAreaOption opt, const AbstractOutput *output, int desktop) const
+{
+    return clientArea(opt, kwinApp()->platform()->enabledOutputs().indexOf(output), desktop);
+}
 
 QRect Workspace::clientArea(clientAreaOption opt, const QPoint& p, int desktop) const
 {

src/workspace.h

@@ -41,6 +41,7 @@ class Window;
 }
 
 class AbstractClient;
+class AbstractOutput;
 class ColorMapper;
 class Compositor;
 class Deleted;
@@ -154,6 +155,7 @@ public:
     QRect clientArea(clientAreaOption, const QPoint& p, int desktop) const;
     QRect clientArea(clientAreaOption, const AbstractClient* c) const;
     QRect clientArea(clientAreaOption, int screen, int desktop) const;
+    QRect clientArea(clientAreaOption, const AbstractOutput *output, int desktop) const;
 
     QRegion restrictedMoveArea(int desktop, StrutAreas areas = StrutAreaAll) const;