Our application style is a container one having three windows:

1. Top: Toolbar with several subsystems, each having submenu action buttons. Action button change the graphic represented in middle window
2. Middle: Graphic application area
3. Botton: Alarms

Is it possible to create a VTScada application with this shape?

See examples in attached images:

Yes.

• The alarm component is a built-in widget.
• The navigation bar you will have to create as a custom widget.
• Then draw both widgets on each screen you develop.

Thanks for your suggestion, but I wanted to have both top and botton fixed and just replace the middle content. I don't want to redraw full screen. Just what it's needed.

You can use opacity scripts and other tricks to make the navigation bar change as you traverse through each page, so it will be functionally equivalent to what you are asking for.

But in reality it will be 2 widgets drawn around each middle section content you want. You could instead, in theory, program the middle section to be a widget, but that is not a practicable path.

Thanks for your ideas.
Perhaps Trihedral should think of a new dynamic widget/page holder. It would be a freeely placeable rectangle able to be loadable with a widget/page stored in a preloaded widget/page library.
Then button action will place/replace desired widget/page into the dynamic widget/page holder

It is something similar to Folders widget, but not reallly the same because we want some fredoom to setup full page (top user defined Buttons & botton Alarm control)

Attached is a try with Folder Widget. It only has a single Folder y top button are no animated. I have no experience to complete the graphic now. This sholud be done:
1- Create new Folder widget. One per top button addressing associated pages per tab. Folder opacity should be linked to a context variable (maybe a masked integer)
2- Buttons on top should act as radio butons. Each button would set the context variable with a exclusive mask to reveal the associated Folder and clear the others