Hide the Preview shortcut in the action panel when the active stage is the PreviewStage.

Also adjust the size of the output button when the Preview button is not visible.

Contributes to CURA-5786.

resources/qml/ActionPanel/OutputProcessWidget.qml

@@ -102,6 +102,8 @@ Column
 
         Cura.ActionButton
         {
+            id: previewStageShortcut
+
             leftPadding: UM.Theme.getSize("default_margin").width
             rightPadding: UM.Theme.getSize("default_margin").width
             height: UM.Theme.getSize("action_panel_button").height
@@ -111,11 +113,12 @@ Column
             textColor: UM.Theme.getColor("primary")
             textHoverColor: UM.Theme.getColor("text")
             onClicked: UM.Controller.setActiveStage("PreviewStage")
+            visible: UM.Controller.activeStage != null && UM.Controller.activeStage.stageId != "PreviewStage"
         }
 
         Cura.OutputDevicesActionButton
         {
-            width: UM.Theme.getSize("action_panel_button").width
+            width: previewStageShortcut.visible ? UM.Theme.getSize("action_panel_button").width : parent.width
             height: UM.Theme.getSize("action_panel_button").height
         }
     }