1. Ensure you register your modeless dialog with NPP (NPPM_MODELESSDIALOG, in Main.cs we call NppFormHelper.RegisterFormIfModeless(Form, bool))
2. The WPF System.Windows.Controls.UserControl should be in an System.Windows.Forms.Integration.ElementHost, which is in a System.Windows.Forms.Form.
3. I’ve subclassed the ElementHost to handle WM_SHOWWINDOW to update the Visible property, and to trigger a (slightly delayed) refresh of the visuals when we get a WM_SIZE. There I invalidate the visuals and update layouts. There may be a way to skip this, but it’s working, so I’m not trying to fix it.
4. In the WPF UserControl, when it’s Loaded, we have to get the presentation source (as a HwndSource) and add a hook to respond to the WM_GETDLGCODE and tell the source that we DLGC_WANTCHARS and DLGC_WANTARROWS, and maybe we also need DLGC_HASSETSEL.

I’ve pulled most of it into a method called MakeModelessDialog. And now for a short recording of it working!

look at what the message [2036] NPPM_MODELESSDIALOG does internally

Puts the window handle of the dialog on a list of window handles which are passed, in turn, to IsDialogMessage in the message loop. If that function returns true, no further message processing is done. If all calls return false, the message is passed to TranslateAccelerator, and if that returns false the message is translated and dispatched normally.

• 13 = 0xD = WM_GETTEXT WParam is always 256 and LParam is always 737269504944
• 135 = 0x87 = WM_GETDLGCODE WParam and LParam are always 0 for these.

I found this page about windows message IDs, which was nice, but then I saw that Visual Studio has some special debugging ToString on System.Windows.Forms.Message` that tells you what the ID means when you mouse over during debugging. Nice. But anyway, still no key-specific events / messages.

Well, because keyboard typing works when I don’t send NPPM_MODELESSDIALOG, but cut/paste/delete works when I do, I’m thinking to look at what the message [2036] NPPM_MODELESSDIALOG does internally, to see if I can combine the good sides of both modes for a WPF version.

• Pressing ‘normal’ keys (e.g. a-z, arrows, 0-9, punctuation) does not send a message to the ElementHostEx, but instead (after I turned the volume up on my laptop), it somehow triggers a bell sound.
• Mouse click comes through with 528 513 36634781 and 33 723656 33619969
• Switching to another program sends 8 0 0, and switching back to NPP sends 1024 0 0
• Pasting into the TextBox works, but does not trigger any messages. Similarly for copying, deleting and backspacing.
• Opening the WPF About window sent 8 1116900 0

I’d like to convert the msg id to a string, I’m not familiar with their values. But there still aren’t that many messages, so perhaps I haven’t set up the dock panel correctly. I’ll try the same thing in the existing Forms version and see what comes up for comparison.

• I like WPF and have 6 years experience in it, but no experience with WinForms.
• It provides strong layout options (e.g. Grid)
• It provides flexible data binding
• It provides Styles.

Some links from others.

@rdipardo is kind of a wizard when it comes to the low-level operation of forms

I’m also unfamiliar with WPF, but I can suggest to @Jonathan-Johansen that hosting the docking form on a WindowsFormsHost might be a better approach. That would at least provide access to a Win32-style window procedure, useful for debugging how (of if) the WM_CHAR message is being handled.

Alternatively, try to expose the window handle of the existing WPF UserControl and pass that to the NPPM_MODELESSDIALOG wrapper instead of the ElementHost (as was tried already ). Or maybe there’s a way for WPF controls to broadcast messages to their child components…🤔?

Oh, it’s interesting - When I don’t call Npp.notepad.AddModelessDialog(host.Handle);, I can type into the TextBox, but I can’t copy/paste with Ctrl+C/Ctrl+V. When I do call Npp.notepad.AddModelessDialog(host.Handle);, I can’t type in, but I can copy/paste with Ctrl+C/Ctrl+V. Curious.

OK, that’s really weird. I’ve never had any problem like that before. @rdipardo is kind of a wizard when it comes to the low-level operation of forms; I’m mentioning him in the hopes that he will be able to give you some advice.

Hi, I’m the maintainer of NppCSharpPluginPack. Glad to hear you’re interested in creating a new variant with WPF, and I hope you’re able to make something you’re happy with.

I don’t know anything about WPF, but I do know that forms (especially docking forms) in a Notepad++ plugin have to do a bunch of annoying fiddly things to ensure that they work correctly. I recommend reading carefully through NppFormHelper.cs and FormBase.cs, because they contain a few methods that you need to create WPF versions of to ensure your forms work correctly.

More specifically, I’m guessing that your keyboard input problem is due to not registering your form with NPPM_MODELESSDIALOG.