Thanks to Dick Kusleika for answering my question and to put me on the right track.
Here is the final solution for anybody having similar demands. It basically works with an ActiveX TextBox to enter the search-string. The macro than is looking in the search-area for all entries containing the search-string. All other filled rows within the search-field will get hidden. This works right away when writing into the TextBox. So, when deleting characters in the search-string the once hidden rows will appear right away if appropriate.
Private Sub TextBox1_Change()
Dim searchArea As Range, searchRow As Range, searchCell As Range
Dim searchString As String
Dim lastRow As Integer
Application.ScreenUpdating = False
searchString = "*" & LCase(TextBox1.Value) & "*"
' unhide rows to have the full search field when editing
Rows.Hidden = False
lastRow = ActiveSheet.Cells(Rows.Count, 1).End(xlUp).Row
Set searchArea = Me.Range("A5", "A" & lastRow) 'Me.Range("A5").End(xlDown))
searchArea.EntireRow.Hidden = True
For Each searchRow In searchArea.Rows
For Each searchCell In searchRow.Cells
If LCase(searchCell) Like searchString Then
searchRow.Hidden = False
Exit For
End If
Next searchCell
Next searchRow
Application.Goto Cells(1), True
Application.ScreenUpdating = True
End Sub
works like a charm.