thank you for this question.
In general the described behaviour is possible. Connection between HMI and signal in REXYGEN is always one-by-one. You have to introduce subsystem with mask and change the mask parameter via HMI, where the connection string will be as follows:
The masked parameter can be used on as many places as desired within the specified subsystem.
thanks for the links, now I understand. You are right, for local HMI you can simply kill Chromium and reload it with a different starting page. For me, this is not appealing at all, but that's not important.
You can always run a bash script from REXYGEN using the EPC function block, killing and restarting Chromium in case of an event. See example 0202-11 for inspiration.
You are right - there is more simple way to center a string than adding variable prefix and suffix.
All you need is:
Add a DisplayString into .svg file (Ctrl + L -> GENERAL -> Drag & Drop "DisplayString.svg")
Hit F8 (or select Text Tool)
Select the DisplayString and center the string:0_1584564636681_6403c868-bfdf-465a-9b80-02571bbdacab-image.png
I believe that's all you need. Now it's on you to build upon this concept.
Btw, what is your motivation for building your very own HMI? From your questions I guess that using the HMI Designer and building the HMI without any hand coding would be much easier and more straightforward for you.