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Rules to Better Interfaces (WinForms Controls) - 15 Rules

These tips designed for Windows Forms haven't lost their relevance in the age of Web UI. If you believe otherwise, let us know (see right nav) and we'll archive them accordingly.

If you still need help, visit Website Design and User Experience and book in a consultant.

  1. Controls - Do you include '-All-' option in your ComboBoxes?

    ComboBoxes are often used for filtering data. It is best to have an '-All-' option to give your user chances to select all data.

    It is important to understand the idea of visual text . In a list you could see either:

    • -None- or
    • No activity assigned

    They both have the same meaning, but the first one is immediately visible whereas the second one must be read.

    If the ID column in your database is a string data type, it is useful to add a constraint to limit the types of characters that it can contain. Adding a constraint can make it simpler to build your front-end, as you won't need to worry about encoding or escaping to handle special characters.

    In SQL Server, you can add a check constraint that limits your column to alphanumeric characters, a hyphen, or underscore using the following T-SQL:

    ALTER TABLE [TableName] ADD CONSTRAINT CK_String_Identifier
        CHECK ([StringIdColumn] NOT LIKE'%[^a-zA-Z0-9_\-]%')

    Combo ALL 1
    Figure: Bad example - No '-All-' option so the user cannot select all data

    Combo ALL 2
    Figure: Good example - Having an '-All-' option gives a user a chance to select all data

    Also, keep it simple!

    Figure: Bad example - '-All Stores-' isn't needed

    Figure: Good example - Keep it as a simple '-All-'

    Figure: Good example - Keeping it simple makes it easy to spot (that there is no filter) when you have multiple fields.

    Read our rule on Always make sure the dimensions All Captions = All.

  2. Controls - Do you include the number of results in ComboBoxes?

    When designing your form, you should try to help your user whenever it's possible. So it's a good idea to include the number of results in ComboBoxes.

    For Windows Forms

    combowf 1
    Figure: Bad example - You can't tell the number of results and there is a scroll bar

    combowf 2
    Figure: Good example - The number of results is clearly displayed. Long text boxes larger than 30 entries, another approach can be employed - putting the common ones at the top

    Figure: Bad example - Firstly because it is manual, plus what about the 4th, 5th, etc most common used countries

    Figure: Bad example – This was a highly unpopular method of the sorting and counting above

    We believe all combos should be able to be sorted ascending/descending and by popularity asc/desc.

    sort alpha numeric
    Figure: Good example - A better way to sort this

  3. Control Choice - Do you use GridView over the CheckedListBox?

    In Web we have:

    In Windows Forms we have a CheckedListBox. With a CheckedListBox you cannot:

    • Sort data - always useful when there are more than about 20 rows
    • Contain much information - can only show one field
    • DataBind - always costs heaps of code

    Figure: Bad Example - The CheckedListBox is limited

    Figure: Good Example - The DataGrid can show much more information (and if you use a 3rd Party eg. Telerik, then it can be pretty too)

    In Windows Forms, the code of DataGrid databinding is easier than that of CheckedListBox.

    ProductsService.Instance.GetAll(Me.ProductsDataSet1)CheckedListBox1.DataSource = Me.ProductsDataSet1.Tables(0)CheckedListBox1.ValueMember = "ProductID"CheckedListBox1.DisplayMember = "ProductName"For i As Integer = 0 To CheckedListBox1.Items.Count - 1Dim checked As Boolean = CType(ProductsDataSet1.Tables(0).Rows(i)("Discontinued"), Boolean)CheckedListBox1.SetItemChecked(i,checked)NextFigure: 8 lines of code to fill a CheckedListBoxProductsService.Instance.GetAll(Me.ProductsDataSet1)Figure: One line of code to fill a DataGridBut the CheckedListBox is useful if only one field needs displaying.

  4. Control Choice - Do you use a GridView (over the ListBox)?

    A GridView provides much richer features than ListBox, you can easily add a checkbox onto the header to allow "check all" functionality, which is impossible for ListBox.

    Figure: Bad Example - Use the ListBox.

    Figure: Good Example - Use GridView and add the enabled checkbox on the header

  5. Control Choice - Do you use ListView over GridView (was DataGrid) for ReadOnly? (Windows Forms only)

    Yes a ListView looks nicer than a DataGrid, but a Datagrid is better because it has more functionality (out of the box that is). With a ListView you cannot:

    • Copy and paste - although you can select a row of data in both controls, you can't copy and paste a whole row from the ListView
    • Sort data - always useful when there are more than about 20 rows
    • DataBind - always saves heaps of code

    So our old rule was to always use the ugly DataGrid (although we were never happy about that).

    Figure: Bad Example - The DataGrid is ugly

    Figure: Good Example - A beautiful ListView - a nicer look over the datagrid

    So the listview looks nicer? If you are not convinced here is another one:

    Figure: Good Example - The appearance of DataGrid and ListView

    But another issue is how much code to write... For ListView you will need to write a bit of code to fill the list view...

    this.listView1.Items.Clear(); // stops drawing to speed up the process, draw right at the end. this.listView1.BeginUpdate(); foreach(DataRow dr in this.dataSet11.Tables[0].Rows) { ListViewItem lvi = new ListViewItem(new string[] {dr[0].ToString(),dr[1].ToString(),dr[2].ToString()}); lvi.Tag = dr; this.listView1.Items.Add(lvi); } this.listView1.EndUpdate();Figure: 8 lines of code to fill a ListViewBut the datagrid is nicer to code... this is because it comes with data binding ability.

    // bind it in the designer first. this.oleDbDataAdapter1.Fill(this.dataSet11);Figure: One line of code to fill a DataGridBut the SSW ListView (included in the .NET Toolkit) is nicer to code with as it comes with data binding ability.

    // bind it in the designer first. this.oleDbDataAdapter1.Fill(this.dataSet11);Figure: One line of code to fill the SSW ListViewSo what is this SSW ListView?

    It is an inherited control that how we implemented the ListView to give us what MS left out.

    • DataBinding
    • Sorting

    So now the rules are:Always use the SSW ListView.Exception: Use the DataGrid when:

    • When not read only - i.e. users will be editing data directly from the cells.
    • You need more than 1 column with checkboxes, or the column with checkboxes can't be the first column. E.g.:
      Figure: One place when you choose a DataGrid over a ListView is when you have 2 checkbox fields

    So in summary, if you don't want users to edit the data directly from the cell, and only the first column need checkboxes, then the ListView is always the better choice.

    We have an example of this in the SSW .NET Toolkit.
    We have a program called SSW Code Auditor to check for this rule.

    Note: We have a suggestion for Microsoft to improve the copy and paste format from a gridview

  6. Control Choice - Do you avoid using Group Box and use a line to organize your form?

    Group box should only be used when you want to notify the user the controls within it are really related, such as radio buttons.

    Figure: Bad Example - Inappropriate use of 'Group Box', there is nothing to be grouped

    Figure: Good Example - Use a line to organize different sections

    Figure: Good Example - VS.NET 2003 Options form, appropriate use of 'Group Box', the radio buttons are related to each other

    vsnet groupbox
    Figure: Good Example - VS.NET 2012 Options form, also appropriate use of 'Group Box'

    In other cases, you should avoid using group box and replace it with a simple line, this will save you some space on the form and help you organize your form more easily.

  7. Controls - Do you use a ToolTip to show the full text of hidden ListView data?

    When you can't see all the text for an item in a ListView you need to expose the full text via a ToolTip.

    Figure: Bad example - Users can't see all the text and the ListView doesn't use a Tooltip

    Figure: Good example - Users can't see all the text, but the ListView shows all the text via a Tooltip

    The code to do this is:

    private ListViewItem hoveredItem;
    private void listView1_MouseMove(object sender, MouseEventArgs e) {
      ListView lv = (ListView) sender;
      ListViewItem item = lv.GetItemAt(e.X, e.Y);
      int columnIndex = 1;
      if (item != hoveredItem) {
        hoveredItem = item;
        if (item == null) {
          toolTip1.SetToolTip(lv, "");
        } else {
          // Make sure the mouse hovered row has the subitem
          if (item.SubItems.Count > columnIndex) {
            toolTip1.SetToolTip(lv, item.SubItems[columnIndex].Text);
          } else {
            toolTip1.SetToolTip(lv, "");
  8. Controls - Do you make the selected/enabled rows stand out in a datagrid?

    Many times you allow a multiple selection in a grid by using a checkbox. When you do this make it easy to see the distinction of a row that is selected and one that is not. Make it subtle by dimming the unselected text.

    Figure: Bad example - Selected rows are not separate from others.

    Figure: Good example - Selected rows are separate from others.

    To make this effect in datagrid, you may need to edit the cellcontentclick event handler code. Example:

    private void DatagridviewRules_CellContentClick(object sender, DataGridViewCellEventArgs e) {
      if (DatagridviewRules.Columns[e.ColumnIndex] is DataGridViewCheckBoxColumn && e.ColumnIndex == 0 && e.RowIndex != -1) {
        bool boolCheckBox = (bool)(DatagridviewRules.Rows[e.RowIndex].Cells[e.ColumnIndex].Value);
        DatagridviewRules.Rows[e.RowIndex].DefaultCellStyle.ForeColor = boolCheckBox ? SystemColors.WindowText : SystemColors.ControlDark;
        DataRowView objDataRowView = (DataRowView) DatagridviewRules.Rows[e.RowIndex].DataBoundItem;
        JobRule.DataTableJobRulesRow objDataRow = (JobRule.DataTableJobRulesRow)(objDataRowView.Row);
        updateRuleIsEnabled(objDataRow.RuleId, boolCheckBox);

    Setting the ForeColor to different ones, like black and gray, can separate the selected rows from others.

  9. Controls - Do you extend the size of your ComboBoxes to show as many results as possible? (Windows Forms Only)

    When designing your form, it's a good idea to help your user whenever it's possible. So it's a good idea to extend your ComboBoxes to show as many results as possible to save your user from scrolling. Also, you should extend the width of the dropdown in order to show the longest items.

    However, you should not extend your ComboBox without limit, normally the maximum number of items should be under 10 and the maximum width of the drop-down should be smaller than your hosting form.

    ComboBox Size 1
    Figure: Bad example - You have to scroll to see all the result, and the long results are cut off

    ComboBox Size 2
    Figure: Good example - The size of the drop down has been extended to allow user to see as much as possible

    Changing the maximum items is easy, just include the following code in your form:

    cbxOUList.MaxDropDownItems = cbxOUList.Items.Count;
    // Changing the drop down size is a bit of tricky
    Graphics g = Graphics.FromHwnd(this.Handle);
    SizeF stringSize = new SizeF();
    stringSize = g.MeasureString(longString, cbx.Font, 600);
    int adjustedSize = cbx.DropDownWidth;
    if (adjustedSize < (int) stringSize.Width) {
      adjustedSize = (int) stringSize.Width;
    cbx.DropDownWidth = adjustedSize;
  10. Controls - Do you use Text Boxes for displaying data?

    Use Label controls to display static text of the application. Eg. "Customer ID:"Use Text Box controls to display data (results of calculations, information, records from a database, etc.).

    The reasons are:

    • users know it is data, not a label of the application
    • users can copy and paste from the field

    PS: One reason web UI's are nice, is that the information is always selectable/copyable.

    BetterInterface LabelCutOff
    Figure: Bad Example - Not only is the data cut off when you are using label, but you can't copy and paste the value

    Figure: Good Example - Using Textbox controls makes the data obvious to users

    As you can see you'll barely know the difference, so start using Textboxes for displaying data, that's good practice.

    More Information

    When using TextBox controls in Windows Forms, set them up like this:

    Figure: Having the 'BorderStyle' Property set to Fixed3D is the best choice visually

    Figure: Make the text box Read-Only (users copying data is OK, changing is silly)

  11. Connection Stream - Do you use a UDL when getting database settings?

    Why do people always invent ways of getting the same old server name and a database name? Look at this image from Speed Ferret - one of my favorite SQL Server utilities.

    Figure: Bad Example - Custom database connection screen in Speed Ferret

    While a nice form, it would have taken quite some developer time to get it right. Not only that, it is a little bit different than what a user has seen before. Now look at this UDL from one of our utilities SSW SQL Auditor:

    Figure: Good Example - Standard Microsoft UDL dialog

    Every developer has seen this before - so use it. Better still, it is only a few lines of code: B-Open UDL Dialog-DH.txt

    Figure: Coming in Visual Studio .NET 2005 Microsoft are yet to release an API to do this

    Need extra information?


    The above cannot be used when you want the user to create a new database. Microsoft does not supply an out of the box UI and there is no third party solution. Only in this case you have to create your own form.

    Figure: SQL Deploy uses its own custom form for "selecting" a database name

  12. Being Pedantic - Do your buttons have a mnemonic?

    A mnemonic for a button is the letter which has an underscore, and the user can press the button using Alt-<char>.

    Figure: Bad example - All buttons without Mnemonic

    Figure: Good example - All buttons with Mnemonic - user can easily choose which button they want without a click

    In Windows Applications, it is quite easy to assign a mnemonic to a button with the "&" character.

    So for the case above, the text would be:

    btnAbout.Text = "&About"
  13. Controls - Do you indicate when fields are "read only" or "calculated"?

    When you are not able to edit a field the field should be greyed out. This visually indicates to the user that the field cannot be changed.

    If you are using Word or Excel, actually locking cells or tables may not be what you require, but you still want to prevent people from directly editing calculations. So make the cells grey and the visual indication should prompt the users what to do.

    Figure: Good Example - Read only fields should be greyed out

    Figure: Good Example - Calculated Fields in Excel should be in Grey

    Of course you should follow the converse, which requires making all editable fields white.

  14. Controls - Do you set row select mode as "FullRowSelect" for DataGridView if it is read only? (Windows Forms Only)

    If you use the DataGridView control which is read only, you had better set row select mode as "FullRowSelect". If the data cannot be modified we can let users select the whole row instead of one column.

    Figure: Bad Example - Row select mode is not "FullRowSelect".

    Figure: Good Example - Row select mode is "FullRowSelect".

    Figure: Changed row select mode to FullRowSelect.

    What's the next step? It's even better if you enable multiple row selection and copying, see Do your List Views support multiple selection and copying on Rules to Better Windows Forms Applications.

  15. Do your controls autopostback?

    When visitors are navigating through your site and they need to make a selection from a control with fixed values, it is best to have the control automatically post back. This makes navigating your site quicker as the user does not have to click other buttons to see the changes which they have made. It is also important to remember that controls which do not have set values, such as text boxes, should have a "Show" button available to click once the visitor is finished entering their data.

    Figure: Bad Example - because the combos can be set to autopostback and should not have a "Show" button.

    Figure: Good Example - because the combo boxes have fixed values and can autopostback.

    Figure: Bad Example - because the text boxes do not have fixed data and thus should have a "Show" button.

    Figure: Good Example - because there is a "Show" button as the text boxes do not contained fixed data.

    Figure: Good Example - because the combos can be set to autopostback while the text boxes have the "Show" button available.

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