Index: ps/trunk/binaries/data/mods/public/gui/session/input.js
===================================================================
--- ps/trunk/binaries/data/mods/public/gui/session/input.js
+++ ps/trunk/binaries/data/mods/public/gui/session/input.js
@@ -1333,10 +1333,14 @@
 
 function OnTrainMouseWheel(dir)
 {
-	if (Engine.HotkeyIsPressed("session.batchtrain"))
-		g_BatchSize += dir / Engine.ConfigDB_GetValue("user", "gui.session.scrollbatchratio");
+	if (!Engine.HotkeyIsPressed("session.batchtrain"))
+	return;
+
+	g_BatchSize += dir / Engine.ConfigDB_GetValue("user", "gui.session.scrollbatchratio");
 	if (g_BatchSize < 1 || !Number.isFinite(g_BatchSize))
 		g_BatchSize = 1;
+
+	updateSelectionDetails();
 }
 
 function getBuildingsWhichCanTrainEntity(entitiesToCheck, trainEntType)