Set Text without clear the fiel

I can’t use the keyword “set Text” bacause it clears the input before set the text, I need a way to set text without clear the input.

what about

def oldText = WebUI.getAttribute(tObject,'value')
WebUI.setText(tObject, oldText+' any new text you want to add')

The input works in some stranger way, when katalon clear the input, It doesn’t let me written on it. The only way is written directly on it without clear it.

in that case use WebUI.sendKeys() function