20260515指摘対応9

src/sh/tuk/sheet/M1.cls

@@ -10,7 +10,10 @@
 Private Sub Worksheet_Change(ByVal Target As Range)
     Dim HasHeaderEdit As Boolean: HasHeaderEdit = CheckHeaderEdit(Me, Target)
     If HasHeaderEdit = True Then Exit Sub
-
+    
+    ' Multi-cell selection not processed
+    If Target.Count > 1 Then Exit Sub
+    
     ' === Column C changes: Create L column dropdown ===
     If Target.Column = 3 And Target.Row >= 7 Then
         Dim cell As Range
@@ -46,6 +49,18 @@ Private Sub Worksheet_Change(ByVal Target As Range)
     End If
 End Sub
 
+' Prevent insert/delete row in header area
+Private Sub Worksheet_BeforeRightClick(ByVal Target As Range, Cancel As Boolean)
+    Dim sheetConfDict As Object: Set sheetConfDict = GetSheetConfig()
+    Dim sheetConf As Object: Set sheetConf = sheetConfDict(Me.CodeName)
+    Dim filterRow As Long: filterRow = sheetConf("FilterRow")
+
+    If Target.Row < filterRow + 1 Then
+        Cancel = True
+        MsgBox "Cannot insert or delete row in header area.", vbExclamation
+    End If
+End Sub
+
 Private Sub Validate(ws As Worksheet, ByVal rowNum As Long, ByVal lastDataRow As Long)
     On Error GoTo ErrHandler