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What is TeX? Do I need to know it to use VRR ?

TeX is a typesetting system written by Donald E. Knuth that was “intended for the creation of beautiful books – and especially for books that contain a lot of mathematics”. Although TeX text objects are one of the main VRR features, you do not need to know TeX to work with VRR and create valuable and sophisticated images in it.

To learn about the TeX typesetting program, see TeX tutorials.

What is Scheme? Do I need to know it to use VRR ?

Scheme is a dialect of the Lisp programming language. in VRR , you need it to write commands in the Scheme console. However, all the important commands are accessible from the GUI, too.

To learn about the Scheme programming language, see the beginning of Scheme to find a list of links to tutorials.

What is the purpose of the .scm example files? How do I open them?

The .scm files contain Scheme scripts (commands usable in the Scheme console). You can either copy and paste them into the console, or load them using the command

     (load "/write/the/filename/here")

in the console. It may produce no output; usually the script defines some new Scheme functions which you can then use in addition the the Scheme and VRR

functions. See The Scheme console to find out how to work with the console and Scheme to learn about VRR Scheme functions.

I have tried to transform an object, but I got the message “This selection cannot be transformed.” What am I doing wrong?

You are trying to transform a dependent object. You might, for example, have snapped one or more anchors of the object to some hangers (not mouse-clicks). If you try to move the object, but not the ones containing the hangers, then moving it would disobey the dependencies.

If you want to free the object from dependencies, rehang its anchors to mouse-clicks (see Anchors and hangers, Anchor rehang, Snap – introducing geometric dependencies).

What is the difference between transformation and anchor rehanging?

Transformations modify the shape of graphic objects, but keep geometric dependencies unchanged. All snapped objects stay snapped in the same way. In contrast to this, rehanging of anchors changes geometric dependencies, removes some of them or creates new. See Transformations of graphic objects, Anchor rehang, What is snap? What is it good for?.

While creating a new object, I clicked a menu command and the object disappeared. How come?

By clicking the menu command, you interrupted the operation of the editor (see The mechanism of creating new graphic objects). Almost all commands are incompatible with the creation of a new graphic object, that they cancel the current operation, which deletes the partially created object. The main reason for this is that the editor uses undo history items to enable the “Step back” feature and does not allow any other actions to interfere with its undo items.

How do you keep a programmer in the shower all day?

Give him a bottle of shampoo which says “lather, rinse, repeat.”

What is the difference between “local” and “global” undo?

The local undo belongs to a page (each page has its independent undo history) and stores actions performed on the contents of the page. The global undo stores the other actions not connected to contents of any page. See Documents and pages.

I clicked “undo” when editing a page, but instead of undoing my last action, it made the page's View disappear. Why?

You actually clicked the “global undo” which undid the last action not connected to the contents of any page. In your case, it was the creation of the edited page, so you deleted it. Using the “global redo” command, you restore the page with all its contents untouched. See Documents and pages.