2 Basic User Interface Principles

2.1 The Mouse

The Selection Button is used to select arguments, to click on command buttons, to double-click and to select commands in all menus but one: the pop-up menu.

The Pop-up Menu Button is used to activate the pop-up menu, that is used during structure editing. The menu pops up when the mouse pointer is located in the codeviewer/editor window and the Pop-up Menu Button is pressed.

2.1.1 UNIX

On UNIX systems the left mouse button is used as the Selection Button and the right most mouse button is used as the Pop-up Menu Button. The middle mouse button has currently no use.

2.1.2 Windows NT/95

On Windows NT/95 systems the left mouse button is used as the Selection Button and the right most mouse button is used as the Pop-up Menu Button. The middle mouse button has currently no use.

2.1.3 Macintosh

On the Macintosh the mouse button is used as the Selection Button and Command-Click is used as the Pop-up Menu Button.

2.2 Selection

Selection is important because most operations in Mjolner are performed in relation to the current selection, which will always be marked in reverse video. There are different ways of selecting parts of a fragment.

When you position the cursor somewhere in the Code editor and click the Selection Button the nearest surrounding structure will be selected and marked as the current selection.

Some examples of how to select:

To select a name:

just place the cursor in the name and click the Selection Button.

To select a complete structure containing keywords :

place the cursor at one of the keywords and click the Selection Button:

Then the resulting current selection becomes:

To select all elements in a list:

place the cursor at one of the list separators e.g. a ';', and click the Selection Button.

To select a sublist:

If a sublist of elements is going to be the current selection, dragging selection is a convenient technique. Dragging selection means clicking with the Selection Button at the starting point of the sublist and keeping the button down while moving the mouse to the ending point of the sublist.

At this point the button is released and the current selection will be set to the selected sublist:

In general the smallest complete enclosing structure will be selected.