docs: horizontal plot split

src/ui_context_help.cpp

@@ -69,9 +69,10 @@ struct HelpHint {
 /// the page is on screen, so the dock needs no hint of its own and the layer has one code path.
 constexpr HelpHint kHelpHints[] = {
     {"plot", "The plot",
-     "Every signal you have switched on is drawn here, one row per group of traces, with all rows "
-     "sharing this one time axis. The wheel zooms about the pointer, a drag pans, and a right-click "
-     "on a row opens that plot's own menu.",
+     "Every signal you have switched on is drawn here, one plot per group of traces, with all plots "
+     "sharing this one time axis. The layout editor (L) adds rows and splits a row into plots side "
+     "by side. The wheel zooms about the pointer, a drag pans, and a right-click on a plot opens "
+     "its own menu.",
      "", &App::area_overlay},
     {"trigger", "The trigger",
      "Freezes the view on an event you describe: a signal, a condition (an edge, a pulse width, a "

src/ui_dock.cpp

@@ -104,7 +104,7 @@ void clear_box(GtkWidget* box) {
 
 /// The strip's cell widths, in characters. Fixed like the dock's, so the strip's chips are as wide with
 /// `--` as with `-123.456 mV` (what does not fit scrolls).
-constexpr int kStripWhoChars = 6;
+constexpr int kStripWhoChars = 7;
 constexpr int kStripTypeChars = 10;
 
 /// A flat text button that opens a slide-over page. It only opens a page, so a rebuild can never free the

src/ui_tour.cpp

@@ -441,7 +441,7 @@ struct TourStep {
 
 constexpr TourStep kTourSteps[] = {
     {"plot", nullptr, "The plot",
-     "Every signal you have switched on is drawn here, all rows sharing one time axis. The wheel "
+     "Every signal you have switched on is drawn here, all plots sharing one time axis. The wheel "
      "zooms, a drag pans, and a right-click on a row opens that plot's own menu.",
      &App::area_overlay},
     {"badges", nullptr, "The badges",