Excel Custom Task Pane not showing

Question

I'm showing a custom task pane in an excel VSTO add-in, I'm building it and showing it as thus:

var ctrl = new CellTaskPane();
var pane = CustomTaskPanes.Add(ctrl, "Custom Sheet");
pane.DockPosition = Office.MsoCTPDockPosition.msoCTPDockPositionRight;
pane.DockPositionRestrict = Office.MsoCTPDockPositionRestrict.msoCTPDockPositionRestrictNoChange;
pane.Visible = true;

This is being done in the ThisAddin.cs file and it working just fine on my machine, both under a Debug session and with the add-in installed via the click-once installer.

However, installing the add-in on a colleague's machine is proving troublesome.

The add-in is functioning and the context menu / ribbon is working perfectly, but the pane just refuses to show.

I have a toggle button on the ribbon which toggles the Visible property on the pane and even clicking that isn't forcing the pane to show.

Any help on this would be greatly appreciated, Google is proving useless for this.

Thanks.

---

I should mention that CellTaskPane is just a UserControl as per the docs on MSDN: http://msdn.microsoft.com/en-us/library/aa942846.aspx

Answer 1

I suggest you try a very, very simple custom task pane first to see if this works. I put together the most simple example I could think of, basically a single text box that gets a value pushed into it and this is returned to the ribbon when a button is pushed.

If you were to try this then I would do it as a new solution. Create a new VSTO project with a "Designer mode" ribbon. Add a toggle button and a normal button below it. Then copy in this code:

ThisAddIn.cs

using System;
using Office = Microsoft.Office.Core;

namespace ExcelAddIn1
{
    public partial class ThisAddIn
    {
        private Microsoft.Office.Tools.CustomTaskPane pane;
        private CellTaskPane ctrl = new CellTaskPane();

        private void ThisAddIn_Startup(object sender, System.EventArgs e)
        {
            pane = CustomTaskPanes.Add(ctrl, "Custom Sheet");
            pane.DockPosition = Office.MsoCTPDockPosition.msoCTPDockPositionRight;
            pane.DockPositionRestrict = Office.MsoCTPDockPositionRestrict.msoCTPDockPositionRestrictNoChange;
            pane.Visible = true;
            pane.VisibleChanged += new EventHandler(taskPaneValue_VisibleChanged);
            ctrl.SetName("test");
        }

        private void taskPaneValue_VisibleChanged(object sender, System.EventArgs e)
        {
            Globals.Ribbons.Ribbon1.toggleButton1.Checked = pane.Visible;
        }

        public Microsoft.Office.Tools.CustomTaskPane TaskPane
        {
            get
            {
                return pane;
            }
        }

        public CellTaskPane MyContainer
        {
            get
            {
                return ctrl;
            }
        }

        private void ThisAddIn_Shutdown(object sender, System.EventArgs e)
        {
        }

        #region VSTO generated code

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InternalStartup()
        {
            this.Startup += new System.EventHandler(ThisAddIn_Startup);
            this.Shutdown += new System.EventHandler(ThisAddIn_Shutdown);
        }

        #endregion
    }
}

Add a new class called CellTaskPane.cs:

using System;
using System.Windows.Forms;
using System.Drawing;
using System.ComponentModel;

namespace ExcelAddIn1
{
    public class CellTaskPane : System.Windows.Forms.UserControl
    {
        public System.Windows.Forms.TextBox test;

        public CellTaskPane()
        {
            InitializeComponent();
        }

        public void InitializeComponent()
        {
            test = new System.Windows.Forms.TextBox();
            test.Location = new System.Drawing.Point(120, 8);
            test.Size = new System.Drawing.Size(232, 20);
            test.TabIndex = 0;
            Controls.AddRange(new System.Windows.Forms.Control[] { test });
            Size = new System.Drawing.Size(375, 150);
        }

        public void SetName(string text)
        {
            test.Text = text;
        }

        public string GetName()
        {
            return test.Text;
        }
    }
}

Add the following code to Ribbon1.cs:

using System;
using Microsoft.Office.Tools.Ribbon;

namespace ExcelAddIn1
{
    public partial class Ribbon1
    {
        private void toggleButton1_Click(object sender, RibbonControlEventArgs e)
        {
            Globals.ThisAddIn.TaskPane.Visible = ((RibbonToggleButton)sender).Checked;
        }

        private void button1_Click(object sender, RibbonControlEventArgs e)
        {
            button1.Label = Globals.ThisAddIn.MyContainer.GetName();
        }
    }
}

Obviously you will need to do a little tweaking to get this to work, I tried to take the default names for a new project and the buttons.

When you run this you should get a custom task pane. When you switch to the "TabAddIn" and click the toggle button it should show/ hide the task pane. When you click the normal button the contents of the only field in the task pane should be copied as the button name. I defaulted this to "test", so even if the task pane isn't visible you can see if it is in memory or not?

I tested this and it appears to work fine. Basically this is just a hacked up version of the examples on MSDN. If you wanted you could probably do this yourself anyway? If nothing else this will enable you to see if there is anything in the more complex ribbon you are working on that causes issues... or if this is a fundamental problem with your colleague's machine.

Answer 2

Well, after following @GaryP's advice, disabling my other add-ins, and thinking that I'd solved the problem (albeit without access to my other add-ins), I discovered that the add-in would disappear whenever I opened more than one workbook.

But at that point, I didn't just get a missing taskpane or a silent fail, I actually got an error:

The taskpane has been deleted or is otherwise no longer valid

So it seems that disabling add-ins isn't solving the problem in itself, but rather disabling add-ins is reducing the number of open workbooks (even if add-ins aren't visible, they can still have a Ribbon handle)...

The underlying cause is the use of SDI in 2013 and later.

So, now I can have all of my add-ins loaded.

Answer 3

Turns out it wasn't anything we were doing directly!

There was another add-in installed (third party) which for some bizarre reason was interfering with the pane being shown (no idea why or how).

Shame that Excel doesn't show any sort of error or at least throw an exception.

Ah well.

Answer 4

I ran into exactly this problem while trying to get the Microsoft sample code for "Walkthrough: Synchronizing a Custom Task Pane with a Ribbon Button" working. Here's a link to the page:

http://msdn.microsoft.com/en-us/library/bb608590.aspx

After starting from scratch about three times and scouring the Internet for a clue as to what I might have been doing wrong, I came across this question and Clint's answer that an add-in was causing his problem. I had a few add-ins enabled, but with some trial and error I found the culprit: Microsoft's own "Analysis Toolpack"!

Once I disabled Analysis Toolpack, the custom pane started appearing and disappearing as expected.

So, as Clint discovered, the first thing you should probably try if you run into this issue is to disable all add-ins and see if that does the trick. If so, then you can go back and begin turning them on until you find the one that is interfering with your custom pane visibility.

Answer 5

I had the same problem and didn't fix it by disableing the analysis toolpack, but, rather i had to move the XLAM out of its installed folder (Break the reference to it, since you couldn't remove it through Excel) and it started working.

I've sense added the files back and it continues to work. Activating the addin does cause my custom taskbar to break. Not sure what this long term fix is here.

Answer 6

Summarizing other answers: It appears that this is due to loading other Add-ins, .XLAM files, etc. These can be loaded from many different places, and you need to check them all, and remove them. You may be able to reenable them later, so back everything up. Here is a checklist:

1. File -> Options -> Advanced -> General -> "At startup, open all files in..." Remove those files and disable the option.
2. File -> Options -> Add-ins -> Check all the Active application add-ins. Near the bottom of the dialog, use the Mange: Excel/Com Add-ins to view the Add-ins and disable or remove them. Even the Microsoft included ones could be causing it, so disable them as well. They do not allow you to remove them, which is fine, as long as they are disabled.
3. C:\Users\$USERNAME\AppData\Roaming\Microsoft\Excel\XLSTART Remove all files from this directory.
4. C:\Users\$USERNAME\AppData\Roaming\Microsoft\AddIns Remove all files from this directory.

After this, try again to load the Add-In. Then, add back the things you need one by one and keep testing. They may break it again, or not, there does not appear to be consensus on what kind of Add-In does and does not break the task pane.

If anyone discovers more places to look for Add-Ins, I will add them to the list.