I18n: add disambiguation contexts

After rBdb87e2a638f9, two contexts were missing:

- VirtualReality, to be used in an add-on
- Constraint, used in the constraints UI

The latter was actually used without being added, which caused errors.
It was reverted in rB31a640027982.

release/scripts/startup/bl_ui/properties_constraint.py

@@ -397,7 +397,7 @@ class ConstraintButtonsPanel:
         sub.prop(con, "invert_z", text="Z", toggle=True)
         row.label(icon='BLANK1')
 
-        layout.prop(con, "mix_mode", text="Mix")
+        layout.prop(con, "mix_mode", text="Mix", text_ctxt=i18n_contexts.constraint)
 
         self.space_template(layout, con)
 
@@ -488,7 +488,7 @@ class ConstraintButtonsPanel:
         self.target_template(layout, con)
 
         layout.prop(con, "remove_target_shear")
-        layout.prop(con, "mix_mode", text="Mix")
+        layout.prop(con, "mix_mode", text="Mix", text_ctxt=i18n_contexts.constraint)
 
         self.space_template(layout, con)
 
@@ -513,7 +513,7 @@ class ConstraintButtonsPanel:
         subsub.prop(con, "eval_time", text="")
         row.prop_decorator(con, "eval_time")
 
-        layout.prop(con, "mix_mode", text="Mix")
+        layout.prop(con, "mix_mode", text="Mix", text_ctxt=i18n_contexts.constraint)
 
         self.draw_influence(layout, con)
 
@@ -1024,7 +1024,7 @@ class ConstraintButtonsSubPanel:
         col.prop(con, "to_min_z" + ext, text="Min")
         col.prop(con, "to_max_z" + ext, text="Max")
 
-        layout.prop(con, "mix_mode" + ext, text="Mix")
+        layout.prop(con, "mix_mode" + ext, text="Mix", text_ctxt=i18n_contexts.constraint)
 
     def draw_armature_bones(self, context):
         layout = self.layout

source/blender/blentranslation/BLT_translation.h

@@ -126,6 +126,10 @@ const char *BLT_translate_do_new_dataname(const char *msgctxt, const char *msgid
 #define BLT_I18NCONTEXT_EDITOR_VIEW3D "View3D"
 #define BLT_I18NCONTEXT_EDITOR_FILEBROWSER "File browser"
 
+  /* Generic contexts. */
+#define BLT_I18NCONTEXT_VIRTUAL_REALITY "Virtual reality"
+#define BLT_I18NCONTEXT_CONSTRAINT "Constraint"
+
 /* Helper for bpy.app.i18n object... */
 typedef struct {
   const char *c_id;
@@ -190,6 +194,8 @@ typedef struct {
         BLT_I18NCONTEXTS_ITEM(BLT_I18NCONTEXT_ID_WINDOWMANAGER, "id_windowmanager"), \
         BLT_I18NCONTEXTS_ITEM(BLT_I18NCONTEXT_EDITOR_VIEW3D, "editor_view3d"), \
         BLT_I18NCONTEXTS_ITEM(BLT_I18NCONTEXT_EDITOR_FILEBROWSER, "editor_filebrowser"), \
+        BLT_I18NCONTEXTS_ITEM(BLT_I18NCONTEXT_VIRTUAL_REALITY, "virtual_reality"),  \
+        BLT_I18NCONTEXTS_ITEM(BLT_I18NCONTEXT_CONSTRAINT, "constraint"), \
     { \
       NULL, NULL, NULL \
     } \