Skip confusing buttons from dom0 and disp template

- Dom0: hide shutdown and pause, technically, shutdown can be used by
  GUIVMs in the future if the action was modified, currently, qubesd
  logs a failure.
- There is no possibility to differentiate between "APPS" and
  "TEMPLATES" tabs, this means that disposable template "Start qube" is
  hidden from both tabs, that is not the intended behavior though but
  would require a redesign to fix. Current behavior though, allows
  searching for "default-dvm" and not have the "Start qube" button
  appear. Therefore, to start the disposable template from the app menu,
  select an application in the "TEMPLATES" tab.

Fixes: QubesOS/qubes-issues#10288
For: QubesOS/qubes-issues#1512

Author: ben-grande

qubes_menu/custom_widgets.py

@@ -466,7 +466,22 @@ def update_state(self, state):
         Update own state (visibility/text/sensitivity) based on provided VM
         state.
         """
+        vm_entry: VMEntry = (
+            self.get_toplevel().get_application().get_currently_selected_vm()
+        )
+        vm_name = vm_entry.vm_name
+        is_dispvm_template = vm_entry.is_dispvm_template
         self.state = state
+
+        if vm_name == 'dom0' or (is_dispvm_template and state != "Running"):
+            self.row_label.set_label(' ')
+            self.set_sensitive(False)
+            self.command = None
+            self.icon.hide()
+            return
+
+        self.set_sensitive(True)
+        self.icon.show()
         if state == 'Running':
             self.row_label.set_label('Shutdown qube')
             self.command = 'qvm-shutdown'
@@ -479,12 +494,11 @@ def update_state(self, state):
             self.icon.set_from_pixbuf(load_icon("qappmenu-shutdown", size=None,
                                                 pixel_size=15))
             return
-        if state == 'Halted':
+        if state == 'Halted' and not is_dispvm_template:
             self.row_label.set_label('Start qube')
             self.command = 'qvm-start'
             self.icon.set_from_pixbuf(load_icon("qappmenu-start", size=None,
                                                 pixel_size=15))
-
             return
         if state == 'Paused':
             self.row_label.set_label('Unpause qube')
@@ -509,8 +523,14 @@ def update_state(self, state):
         Update own state (visibility/text/sensitivity) based on provided VM
         state.
         """
+        vm_entry: VMEntry = (
+            self.get_toplevel().get_application().get_currently_selected_vm()
+        )
+        vm_name = vm_entry.vm_name
+
         self.state = state
-        if state == 'Running':
+
+        if state == 'Running' and vm_name != 'dom0':
             self.row_label.set_label('Pause qube')
             self.set_sensitive(True)
             self.command = 'qvm-pause'