assembly: disable auto solve when workbench is not active

assembly.py

@@ -2788,7 +2788,8 @@ class Assembly(AsmGroup):
     @classmethod
     def canAutoSolve(cls):
         from . import solver
-        return gui.AsmCmdManager.AutoRecompute and \
+        return gui.AsmCmdManager.WorkbenchActivated and \
+               gui.AsmCmdManager.AutoRecompute and \
                FreeCADGui.ActiveDocument and \
                not FreeCADGui.ActiveDocument.Transacting and \
                not FreeCAD.isRestoring() and \

gui.py

@@ -138,6 +138,7 @@ class AsmCmdManager(ProxyType):
     Toolbars = OrderedDict()
     Menus = OrderedDict()
     _defaultMenuGroupName = '&Assembly3'
+    WorkbenchActivated = False
 
     @staticmethod
     def getToolbarParams():

init_gui.py

@@ -29,11 +29,13 @@ class Assembly3Workbench(FreeCADGui.Workbench):
 
     def Activated(self):
         from .gui import AsmCmdManager
+        AsmCmdManager.WorkbenchActivated = True
         for cmd in AsmCmdManager.getInfo().Types:
             cmd.workbenchActivated()
 
     def Deactivated(self):
         from .gui import AsmCmdManager
+        AsmCmdManager.WorkbenchActivated = False
         for cmd in AsmCmdManager.getInfo().Types:
             cmd.workbenchDeactivated()