WPF richtextbox no line break in first line?

I experienced a weird bug and am unable to solve it.

To reproduce:

1. Create new wpf project

2. Add richtextbox, name it e.g. "rtb"

3. Append a text with line break at the end 3 times. For example

rtb.AppendText("lol\n");
rtb.AppendText("lol\n");
rtb.AppendText("lol\n");

4. Now start the application. Notice how everything works fine and there are three lines saying "lol".

5. Now clear the richtextbox before appending the lines:

rtb.Document.Blocks.Clear();
rtb.AppendText("lol\n");
rtb.AppendText("lol\n");
rtb.AppendText("lol\n");

6. Start the application again. Notice that the output is no longer

lol

but this time

lollol

lol

so essentially the "\n" for the first "lol" was added after the next "lol", lol?

Do you know what's going on because I don't. I'd expect it to output

lol

and I don't see why clearing the text content makes the richtextbox behave like this. I guess it's a bug but I don't understand why it's happening or how can I solve this.

It can't be because of "rtb.Document.Blocks.Clear()" as I've tried other methods for clearing the richtextbox as well, like

rtb.SelectAll();
rtb.Selection.Text = "";

and other approaches. However, none of them afterwards printed the text correctly. Now in this simple scenario, doing

rtb.Document.Blocks.Clear();
rtb.AppendText("lol\nlol\nlol\n");

(writing all 'lol's at once) actually does fix the issue. However I obviously don't just print out lol, but I have to call "AppendText" multiple times, resulting in incorrect output. Any ideas? Or where should I submit a bug report? Thanks.

4 Replies

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Dharmraj Thakur8y ago
Accepted answer
By default it require one break line...

Try this it will work
rtb.Document.Blocks.Clear();
rtb.AppendText("\n");
rtb.AppendText("lol\n");
rtb.AppendText("lol\n");
rtb.AppendText("lol\n");
+2
Guest User8y ago
Thanks it works now! :)
Why does it require a line break though? And why is the line break after the first lol removed? it seems like it will just move the "\n" after the first "lol" to the very beginning if there isn't a "\n" at the start, which is even more confusing - but whatever.
+2
Guest User8y ago
@Amit unfortunately in WPF the RichTextBox doesn't have a Text property like in Windows Forms: https://stackoverflow.com/questions/957441/richtextbox-wpf-does-not-have-string-property-text
Thanks for the input though.
+2
Amit Gupta8y ago
Have you tried clearing your rtb with rtb.Text = "";
+2