inherit or Subclass TextBox to disable Paste on TextBox

Question

I made an ButtonEditor usercontrol with one TextBox and one Button. How to disable TextBox's paste operation from Right Click Menu "Paste" ? Right now, my method is to create a Class called "CustomMenuTextBox.cs" which Subclassed msg "WM_INITMENU" and "WM_INITMENUPOPUP" to call Win32 API EnableMenuItem. But I don't know how to implement two inherits.

The ButtonEditor.cs look like:

internal partial class ButtonEditor : UserControl
{  
   //add a textbox and a button from toolbox and some codes...
}

The CustomMenuTextBox.cs look like:

internal partial class CustomMenuTextBox : TextBox
{
    protected override void WndProc(ref Message m)
    {
        if (m.Msg == 0x0093 /*WM_UAHINITMENU*/ || m.Msg == 0x0117 /*WM_INITMENUPOPUP*/ || m.Msg == 0x0116 /*WM_INITMENU*/)
        {
            IntPtr menuHandle = m.Msg == 0x0093 ? Marshal.ReadIntPtr(m.LParam) : m.WParam;

            // MF_BYPOSITION and MF_GRAYED
            mAPI.EnableMenuItem(menuHandle, 4, 0x00000400 | 0x00000001);
        }

        base.WndProc(ref m);
    }
}

I got an error:

internal partial class ButtonEditor : CustomMenuTextBox, UserControl

I know I may make totally wrong way for disable Paste operation for TextBox right click menu. Please show me the right way.

It is not clear what you're asking. Why are you trying to make your editor _inherit_ the `CustomMenuTextBox` class? The editor _has a_ `TextBox`, so if you want to customize that `TextBox`, it stands to reason the editor should instead _have a_ `CustomMenuTextBox`, rather than for it to _be a_ `CustomMenuTextBox` as you're trying to do here. — Peter Duniho, Sep 27 '17 at 00:39
OK. How to Subclass TextBox (disable right click menu "Paste" item) inside ButtonEditor? — qtg, Sep 27 '17 at 00:44
_"How to Subclass TextBox...inside ButtonEditor"_ -- what don't you understand how to do? Your question already shows a class that subclasses `TextBox`. So all that seems to be left is _"...inside ButtonEditor"_, and the answer to that is simply to put an instance of `CustomMenuTextBox` in the `ButtonEditor` instead of a `TextBox` as you appear to have now. The way you put a `TextBox` in your `ButtonEditor`, just do that except use `CustomMenuTextBox` instead. — Peter Duniho, Sep 27 '17 at 00:51
I seems to understand what you teach me. But I am not so clear. I have many codes for txtEditor inside ButtonEditor. How to modify? For example: private void txtEditor_KeyPress(object sender, KeyPressEventArgs e) { //...} — qtg, Sep 27 '17 at 01:02
Why do you have to modify any of that? Since your `CustomMenuTextBox` _is a_ `TextBox`, all of the code that worked with a `TextBox` will still work with a `CustomMenuTextBox`. — Peter Duniho, Sep 27 '17 at 01:12
I understand now. I have changed the ButtonEditor.designer.cs. //private System.Windows.Forms.TextBox txtEditor; private CustomMenuTextBox txtEditor; this.txtEditor = new CustomMenuTextBox();//System.Windows.Forms.TextBox(); — qtg, Sep 27 '17 at 01:24

qtg · Answer 1 · 2017-09-27T12:47:45.830

I have tested the code snippets on stackoverflow.com, it does work to disable "Paste" menu item for a textbox. However,I just tested on Windows 10 32 bits. The Subclassed message is WM_UAHINITMENU (0x0093), but I couldn't find any info about Windows message "WM_UAHINITMENU" on MSDN.

Credit to @demidov and @CodeCaster and thanks Peter Duniho for proper implementation.

put some codes inside you control and may modify your xxx.designer.cs:

internal partial class CustomMenuTextBox : TextBox
    {
        protected override void WndProc(ref Message m)
        {
            if (m.Msg == 0x0093 /*WM_UAHINITMENU*/ || m.Msg == 0x0117 /*WM_INITMENUPOPUP*/ || m.Msg == 0x0116 /*WM_INITMENU*/)
            {
                IntPtr menuHandle = m.Msg == 0x0093 ? Marshal.ReadIntPtr(m.LParam) : m.WParam;

                // MF_BYPOSITION and MF_GRAYED
                mAPI.EnableMenuItem(menuHandle, 4, 0x00000400 | 0x00000001);
            }

            base.WndProc(ref m);
        }
    }

inherit or Subclass TextBox to disable Paste on TextBox

1 Answers1