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How to PgUp/PgDn with SendKeys to a foreground textbox

I am trying to page up/down the contents of a simple textbox control in a simple Windows Form on NET 6.0, but something is wrong. Textbox shortcuts are enabled (probably why SendKeys.SendWait("^a"); works) and readonly is false.
I have a method (not on the UI thread) that I call to SendKeys.SendWait("{PgUp}"); to the foreground app (which is both the key sender and textbox (with focus) receiver.
If I type PgUp on the keyboard, the textbox pages up as expected.
If I SendKeys.SendWait("^a");, the textbox selects all text as expected.
If I Sendkeys.SendWait("{PgUp}");, the textbox adds a blank line to the bottom of the text.
From this I conclude that my code is working because it sends "^a" and the textbox receives it and selects all text. But somehow the textbox does not handle the "{PgUp}" key, even though it does when the PgUp key is sent by the keyboard.
I've read easily a dozen articles and posts on the web and SO that talk about paging using scrolling events, positioning the caret and then scrolling to the caret, and so on. But none of them say anything about why SendKeys(^a) and keyboard PgUp would work but SendKeys.SendWait("{PgUp}") would fail.
Can anyone tell me what I'm doing wrong and maybe what I need to do (or read) to fix it? Thank you
UPDATE: Jimi asked for some code, so here is the code that I use to send the ^a and the {PgUp} keys. I know this is not on the UI thread because it is executed from a voice-driven recognizer thread. The app is a voice-driven app that displays content in the textbox by textbox.AppendLines calls. I was trying to PgUp and PgDn the multi-line textbox by voice as well.
When I tried to use Send (I normally use .SendWait for everything in other programs), I received the following error message:
System.InvalidOperationException: 'SendKeys cannot run inside this
application because the application is not handling Windows messages.
Either change the application to handle messages, or use the
SendKeys.SendWait method.'
It is true that my app does not intercept Windows messages. I can't figure out why the app can receive and properly process my keyboard keys, and my "^a' shortcut keys, but not the SendWait("{PgUp}") key.
internal static void
HelperPageUp() {
var keys = "{PgUp}";
keys = "^a";
SendKeys.SendWait(keys);
}
I'm starting to think that {PgUp} is never handled by a textbox or control. Instead, probably {PgUp} must be handled by logic in a case statement that converts PgUp "orders" into sets of actions that implement whatever PgUp means to the app that receives the PgUp key. So maybe I will have to add a keystroke handler to the form. Maybe something like this:
textBox1_KeyUp(object sender, KeyEventArgs e) {
// identify the special key and implement what it means
if (e.KeyCode == Keys.PageDown) {
...
e.Handled = true;
}

Yes, my thought at the end of the question was correct. The ^a was handled by the textbox because I had textbox.EnableShortcuts=true;, so the textbox handled the popular ^a shortcut. But keys like {PgUp} are a different matter; they are not included in shortcuts.
The solution was to write code to handle the {PgUp} key explicitly in the form. Here is my code that worked.
void
textBox1_KeyUp(object sender, KeyEventArgs e) {
if (e.KeyCode == Keys.PageUp) {
// page the viewport up; watch for end of content
var charIndex = textBox1.SelectionStart;
var lineIndex = textBox1.GetLineFromCharIndex(charIndex);
// move 20 lines up, but not past zero
var newLine = lineIndex - 20;
var newIndex = Math.Max(0, newLine);
// set the new anchor and scroll to it
var newAnchor = textBox1.GetFirstCharIndexFromLine(newIndex);
textBox1.Select(newAnchor,0);
textBox1.ScrollToCaret();
e.Handled = true;
}

allowing * character in textbox C# WPF

I am creating a rs232 dial pad in a WPF. The problem I am running into is with the star character. I don't know how to ask the question correctly because all I am getting results for are "password characters only".
Ultimately I'm trying to add the "*" programmatically. It does not matter if I used the keyboard or the virtual button. Whenever the character is added the program freezes. The debugger isn't pointing to anything and seems like its still waiting for instruction.
Any ideas?
Im adding the star with
textBox.text="*";

Honestly I am not sure what happened. I started a new WPF and it worked. So i removed auto generated method all together and recreated it. Now it works. The entire method looked like this
private void button_Click(object sender, RoutedEventArgs e)
{
textBox.Text = "*";
}
No clue but it works. Thank you for the replies

C# Programmatically send two keys when you are already pressing another one

I'm making my own multiple clipboard copy/paste tool which runs in background, and I've finally achieved it, it's working.
this is how it works,
when Capslock it's pressed, if I press CTRL+1 I make a CTRL+C programmatically ( with SendKeys) and save the clipboard on my list with correct position
when capslock it's not pressed, if I press CTRL+1 I make a CTRL+V programmatically ( with send keys) by using the latest data in clipboard on the correct list position.
Now it's fine, but I want to make a little change, I don't want to use capslock, but I want to press another key, like ALT or SHIFT, but if you keep pressing a key which is not the CTRL and then you do a CTRL+C, it does not work.
Anyone have any advice to this dumb thing?
Thanks guy

If you don't mind using WinApi functions, you can use RegisterHotKey and UnregisterHotKey functions.
They allow you to register and unregister global shortcuts of your choice. This way you'll get notified about a shortcut being pressed even if your application is running in background and doesn't have the focus on itself.
You can find more information about both functions on pinvoke here and here. There is even some sample application code so you can see how to use them.
NOTE: Remember to unregister all the shortcuts that you've registered on application exit.

You can use a flag for the select key. When you check to see what keys are pressed then:
something like the following pseudo code should do the trick:
if(select key)
{
this.selectKey = true;
}
else
{
if(ctrl key)
{
//do whatever you would normally do here
}
this.selectKey = false;
}

how to identity a click out of the form and 1 more question

i want to build a simple program which help you selecting pictures.
if you have lot of picture and you want to choose some of them then you see them 1 by 1 and when you see a picture you would lik to save on other folder on your pcyou just press a button ,lets say f5 and the program copy the phtot from the path you looking at to the destiny folder.
for that program i need to ask how to know if someone pressed f5 out of the form area and how to know in which path the user looking at.(i want to build it for myself atm so if its help i look with microsoft office picture manager)
about the clicking i search a little and get something named global clicking and hooks which i dont understand so much and about identify the path i have no idea .
tyvm for help:)

I'm not sure I follow the rest -- but if you want to capture the keypress event, simply add an event handler for KeyPress and determine if the pressed key is equal to the F5 button by using the Keys constants.

Here is a project on Code Project that does exactly what you need :)
http://www.codeproject.com/KB/cs/globalhook.aspx

The key press event wont work with the following (Link):
TAB
INSERT
DELETE
HOME
END
PAGE UP
PAGE DOWN
F1-F2
ALT
Arrow keys
Note: I think there is a typo on the page and the F1-F2 really should be F1-F12.
When you decide the key for your on key press event for the form area you are talking about it will look like this:
private void Form_KeyPress(object sender, KeyPressEventArgs e)
{
if(e.KeyChar == [keypressvalue])
{
//do your copy logic
}
}
[keypressvalue] will be the code for F5 if you choose to use this. I have found a mix of values for this (i could not get my test keypress event to pick up the F5 event, hence my note above) so i recommend running the event once with a brake point, inspecting the code, then brake and update your code, then test your logic.
Like the rest i'm not really sure what you want your custom logic to do.
Clairifcation: I'm trying to understand your question, so what you want is: When in Microsoft Picture Manager when you press F5 you want the image that is currently being viewed to be moved to a particular directory? Now if you are writing your own picture viewer and move software then i think we can help if it is the above i'm not really sure you can do that.

C# textbox deletion question

I am working on a project that I use textbox as telnet terminal.
The terminal has "->" as the command prompt in the textbox.
Is there a way to disable the delete or backspace once it reach the "->" prompt?
I don't want to delete the command prompt.
Thanks

Dave is right.
The best way to do this is to make a label on the left side of the textbox that says ->.
You can remove the textbox's border and put them both in a white (or non-white) box to make it look real.
This will be much easier for you to develop and maintain, and will also be more user-friendly. (For example, the Home key will behave better)

Two options:
Make the prompt ("->") an image or label, instead of being part of the textbox.
If it's a web app, handle the textchanged event in javascript and cancel the textchanged if it represents a deletion of the prompt. If its not a web app, do the same thing in c# rather than JS.

You could always make sure that when deleting, the index of the character you're deleting is > 1 (since -> would occupy positions 0 & 1)

This is a naive example, but you should be able to figure it out from here. You can peak at the keydown event and cancel it, when desired.
private void testTextBox_KeyDown(object sender, KeyEventArgs e)
{
if (e.KeyCode == Keys.Back && testTextBox.SelectionStart == 2)
{
e.SuppressKeyPress = true;
}
}