[color] Fixed throttle trim switch setting

radio/src/datastructs.h

@@ -672,6 +672,22 @@ PACK(struct ModelData {
         return thrTrimSw + MIXSRC_FIRST_TRIM;
     }
   }
+
+  void setThrottleStickTrimSource(int16_t src)
+  {
+    // The order here is TERA, so that 0 (default) means Throttle
+    switch (src) {
+      case MIXSRC_TrimThr:
+        thrTrimSw = 0;
+        break;
+      case MIXSRC_TrimRud:
+        thrTrimSw = 2;
+        break;
+      default:
+        thrTrimSw = src - MIXSRC_FIRST_TRIM;
+        break;
+    }
+  }
 });
 
 /*

radio/src/gui/colorlcd/model_setup.cpp

@@ -1160,7 +1160,10 @@ void ModelSetupPage::build(FormWindow * window)
 
     // Throttle trim source
     new StaticText(window, grid.getLabelSlot(true), STR_TTRIM_SW);
-    new SourceChoice(window, grid.getFieldSlot(), 0, NUM_TRIMS - 1, GET_SET_DEFAULT( g_model.thrTrimSw));
+    new SourceChoice(
+        window, grid.getFieldSlot(), MIXSRC_FIRST_TRIM, MIXSRC_LAST_TRIM,
+        [=]() { return g_model.getThrottleStickTrimSource(); },
+        [=](int16_t src) { g_model.setThrottleStickTrimSource(src); });
     grid.nextLine();
   }