Merge pull request #2477 from LinuxCNC/halscope-fix-vert-scale

halscope: fix initialization of gain/scale for new channels

Author: SebKuzminsky

src/hal/utils/scope_vert.c

@@ -1094,6 +1094,11 @@ void channel_changed(void)
     gtk_adjustment_set_lower(adj, chan->min_index);
     gtk_adjustment_set_upper(adj, chan->max_index);
     gtk_adjustment_set_value(adj, chan->scale_index);
+
+    // Call the `scale_changed()` callback once by hand to initialize
+    // the new channel's scale/gain.
+    scale_changed(adj, NULL);
+
     /* update the channel number and name display */
     snprintf(buf1, BUFLEN, "%2d", vert->selected);
     name = chan->name;