Keyboard navigation with nested TabStrips

Comments (7)

Posted 16 years ago by Actipro Software Support - Cleveland, OH, USA

Hi Shaun,

If you have KeyboardNavigationEnabled for both, the ProcessCmdKey method will trap the Ctrl+Tab and Ctrl+Shift+Tab keys right now. You can create a class that inherits TabStrip and override that method to provide the additional functionality you desire.

Actipro Software Support

Posted 16 years ago by Shaun Martin - RevQ

Ok, thanks for the reply, sorry for the delay, here's what I did.

As you suggested I created a derived TabStrip class with an overridden ProcessCmdKey method which cycled the tabs on Ctrl+Alt+Tab. That was with the *inner* of the two nested TabStrips. The problem is that I want Ctrl+Tab to cycle the tabs in the *outer* TabStrip - the inner TabStrip should inspect the key command (which it does) and if it's not Ctrl+Alt+Tab, then the key command is passed to the outer TabStrip. What I'm seeing is that if the inner TabStrip sees the command/message/keys/whatever, the outer TabStrip doesn't. Make sense? I need some way to pass the command along (bubble up).

Thanks for your help.

Here's my ProcessCmdKey override:


        protected override bool ProcessCmdKey(ref System.Windows.Forms.Message m, System.Windows.Forms.Keys keyData)
        {
            if (m_useAltKeyNav)
            {
                if (keyData == (System.Windows.Forms.Keys.Control | System.Windows.Forms.Keys.Alt | System.Windows.Forms.Keys.Tab))
                {
                    if (this.Pages != null && this.Pages.Count > 1)
                    {
                        this.SelectedIndex = (this.SelectedIndex + 1) % this.Pages.Count;
                    }

                    return true;
                }
                else
                {
                    return false;
                }
            }
            else
                return base.ProcessCmdKey(ref m, keyData);
        }

Posted 16 years ago by Shaun Martin - RevQ

I apologize - some of the above info isn't correct. What I have is NOT two nested TabStrips, but instead a TabStrip nested [in a document] in a DockManager, where the DockManager has the following settings:

DocumentMdiStyle = Tabbed
KeyboardNavigationEnabled = true
NextWindowNavigationEnabled = true
NextWindowNavigationType = DocumentWindow

All the behavior I've described is correct though...sorry for the confusion.

Posted 16 years ago by Actipro Software Support - Cleveland, OH, USA

Shaun,

Why don't you just override ProcessCmdKey on the inner TabStrip and if you see Ctrl+Tab then do not call the base method? That would block the inner one from grabbing it and would probably allow it to bubble up, no?

Actipro Software Support

Posted 16 years ago by Shaun Martin - RevQ

Currently if m_useAltKeyNav is true (meaning we're looking for Ctrl+Alt+Tab), we don't call the base. I tried commenting out the base call, just in case my logic was wrong, and I still see the same behavior. Even though we're not calling the base, it appears to me that the overridden ProcessCmdKey is not allowing the message/event/command to bubble up. Or perhaps just setting KeyboardNavigationEnabled to true is causing the message to always be trapped?

In an earlier post, I mentioned that if the inner TabStrip had only one tab, the key command would bubble up. This was wrong. In my test, the inner TabStrip that only had one tab also had KeyboardNavigationEnabled set to false. If I set it to true, key commands don't bubble up, even with just one tab/page in the TabStrip.

Again, I appreciate your help.

Posted 16 years ago by Actipro Software Support - Cleveland, OH, USA

Just looked at the code again. ProcessCmdKey is the only method in TabStrip in which we look for Ctrl+Tab and we only do that if KeyboardNavigationEnabled is true.

Maybe you should change your code above to not "return false;" in that one case but also call the base method in that case like in your other "else"?

Actipro Software Support

Posted 16 years ago by Shaun Martin - RevQ

No, calling the base how you suggested would essentially be the same as using the base implementation of ProcessCmdKey when anything other than Ctrl+Alt+Tab is pressed. I tried it and it caused my inner TabStrip to switch pages on BOTH Ctrl+Alt+Tab and Ctrl+Tab.

I found a solution though, albeit a bit of a hack. I still believe that if KeyboardNavigationEnabled is enabled, ANY implementation of ProcessCmdKey (base or overridden) will prevent the key command from bubbling up. That's the basis for my workaround (I removed my m_useAltKeyNav flag for clarity) which turns off KeyboardNavigationEnabled briefly while the base ProcessCmdKey is called so that the key command will bubble up:


        protected override bool ProcessCmdKey(ref System.Windows.Forms.Message m, System.Windows.Forms.Keys keyData)
        {
            if (keyData == (System.Windows.Forms.Keys.Control | System.Windows.Forms.Keys.Alt | System.Windows.Forms.Keys.Tab))
            {
                if (this.Pages != null && this.Pages.Count > 1)
                {
                    this.SelectedIndex = (this.SelectedIndex + 1) % this.Pages.Count;
                }

                return true;
            }
            else
            {
                this.KeyboardNavigationEnabled = false;
                bool result = base.ProcessCmdKey(ref m, keyData);
                this.KeyboardNavigationEnabled = true;
                return result;
            }
        }

Anyway, thanks for your help.

The latest build of this product (v24.1.1) was released 7 months ago, which was after the last post in this thread.

Comments (7)

Add Comment