The native RichEdit control prefers CR as the EndOfLine character, so your options are either to assign the entire string upfront:
Var s As String
s = "Some test" + EndOfLine
s = s + EndOfLine + "Some other text"
Or with a change to txaTwo.Opening using EndOfLine.CR
me.Text = ""
me.Text = "Some test" + EndOfLine.CR
me.Text = me.Text + EndOfLine.CR + "Some other text"
But all this is not relevant since the complaint is not what kind of workaround you can do…either Xojo is Cross platform tool or it is not.
So if getting “EndOfLine” on Windows TextBox, then if the native RichEdit control under the hood has issue with it then Xojo should obviously detect the EndOfLine and convert it to EndOfLine.CR.
It is not helpful for the Xojo cross platform developer to have to just “know” this and have to do tons of #if TARGET_WINDOWS when filling out simple text into a TextBox.
The main problem is Xojo using a RichEdit control all the time instead of a multiline Edit control. A LOT of problems could be avoided using the right control. A formated text control should be separated from the multiline textbox