PyDoc: bpy.types.Operator docs - add note on execution context

Clarify the default behavior when invoke and execute is called.

Ref: !135854

doc/python_api/examples/bpy.ops.py

@@ -14,6 +14,10 @@ Common return values are ``{'FINISHED'}`` and ``{'CANCELLED'}``, the latter
 meaning that the operator execution was aborted without making any changes or
 saving an undo history entry.
 
+If operator was cancelled but there wasn't any reports from it with ``{'ERROR'}`` type,
+it will just return ``{'CANCELLED'}`` without raising any exceptions.
+If it had error reports, then it will raise a ``RuntimeError`` including all report messages.
+
 Calling an operator in the wrong context will raise a ``RuntimeError``,
 there is a poll() method to avoid this problem.
 

doc/python_api/examples/bpy.types.Menu.py

@@ -14,10 +14,12 @@ convention for menus.
 
 .. note::
 
-   Menus have their :class:`Layout.operator_context` initialized as
-   'EXEC_REGION_WIN' rather than 'INVOKE_DEFAULT' (see :ref:`Execution Context <operator-execution_context>`).
+   Menus have their :class:`UILayout.operator_context` initialized as
+   'EXEC_REGION_WIN' rather than 'INVOKE_REGION_WIN' (see :ref:`Execution Context <operator-execution_context>`).
    If the operator context needs to initialize inputs from the
    :class:`Operator.invoke` function, then this needs to be explicitly set.
+   When a menu is added to UI elements such as a panel or header,
+   the operator execution context will be inherited from them.
 """
 import bpy
 

doc/python_api/examples/bpy.types.Operator.2.py

@@ -9,6 +9,13 @@ execute().
 Some operators don't have an execute() function, removing the ability to be
 repeated from a script or macro.
 
+When an operator is called via :mod:`bpy.ops`, the execution context depends
+on the argument provided to :mod:`bpy.ops`. By default, it uses execute().
+When an operator is activated from a button or menu item, it follows
+the setting in :class:`UILayout.operator_context`. In most cases, invoke() is used.
+Running an operator via a key shortcut always uses invoke(),
+and this behavior cannot be changed.
+
 This example shows how to define an operator which gets mouse input to
 execute a function and that this operator can be invoked or executed from
 the python api.

source/blender/makesrna/intern/rna_ui.cc

@@ -1706,6 +1706,10 @@ static void rna_def_ui_layout(BlenderRNA *brna)
   RNA_def_property_enum_items(prop, rna_enum_operator_context_items);
   RNA_def_property_enum_funcs(
       prop, "rna_UILayout_op_context_get", "rna_UILayout_op_context_set", nullptr);
+  RNA_def_property_ui_text(prop,
+                           "Operator Context",
+                           "Typically set to 'INVOKE_REGION_WIN', except some cases "
+                           "in :class:`bpy.types.Menu` when it's set to 'EXEC_REGION_WIN'.");
 
   prop = RNA_def_property(srna, "enabled", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_funcs(prop, "rna_UILayout_enabled_get", "rna_UILayout_enabled_set");