RichTextBox Color problem

[BAILANDO]

Hello, i have code where i call function on textchanged in richtextbox, but here is one problem, when i input first character, it works as i expected, but when i input second characted, then full text is green, dont know why. How to fix this please?

private: System::Void richTextBox_srv_output_TextChanged(System::Object^  sender, System::EventArgs^  e) {
		int riadky = richTextBox_srv_output->Lines->Length;
		for (int i = 0; i < riadky; i++)
		{
			String^ line;
			line = richTextBox_srv_output->Lines[i]->ToString();
			if (line->Contains("//"))
			{
				richTextBox_srv_output->Find(line);
				richTextBox_srv_output->SelectionColor = Color::LightGreen;
			}
		}
	}

[BAILANDO]

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[BAILANDO]

with this it works
richTextBox_srv_output->Clear();
richTextBox_srv_output->AppendText(output);

but i see on Clear blinking text and its annoying when you write fast. its another way how to do this please? Thanks