A simple GUI for editing a string inside arduino IDE

Create a simple GUI which can edit a specific string of code inside an Arduino IDE. The idea is to let the user edit that specific string without interacting with the IDE, when pressing apply, it should just replace a specific string ( here it is " ENTER A PHRASE" ) so that he can change it as many time as he wishes. The best solution is such that does not change with the current arduino IDE code, but simply deletes the current string and injects the user input( the code shown in the graphic is the actual code). It has to look decent ( it is a GUI after all ).