Fixed typos in comments

Source/VirtualTrees.WorkerThread.pas

@@ -65,7 +65,7 @@ class procedure TWorkerThread.Dispose(CanBlock: Boolean);
   WorkerThread.Terminate();
   SetEvent(WorkerThread.FWorkEvent);
   LRef := WorkerThread;
-  WorkerThread := nil; //Will be freed usinf TThreaf.FreeOnTerminate
+  WorkerThread := nil; //Will be freed usinf TThread.FreeOnTerminate
   if CanBlock then
     LRef.Free;
 end;

Source/VirtualTrees.pas

@@ -9654,19 +9654,20 @@ procedure TVTHeader.AutoScale();
 begin
   if toAutoChangeScale in Treeview.TreeOptions.AutoOptions then
   begin
-    // Find the largest Columns[].Spacing
+    // Ensure a minimum header size based on the font, so that all text is visible.
+    // First find the largest Columns[].Spacing
     lMaxHeight := 0;
     for I := 0 to Self.Columns.Count - 1 do
       lMaxHeight := Max(lMaxHeight, Columns[I].Spacing);
-    // Calculate the required size based on the font, this is important as the use migth just vave increased the size of the icon font
+    // Calculate the required height based on the font, this is important as the user might just have increased the size of the system icon font.
     with TBitmap.Create do
       try
         Canvas.Font.Assign(FFont);
         lMaxHeight := lMaxHeight {top spacing} + (lMaxHeight div 2) {minimum bottom spacing} + Canvas.TextHeight('Q');
       finally
         Free;
       end;
-    // Get the maximum of the scaled original value an
+    // Get the maximum of the scaled original value and the minimum needed header height.
     lMaxHeight := Max(lMaxHeight, FHeight);
     // Set the calculated size
     Self.SetHeight(lMaxHeight);