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Motif and CDE 2.1 Style Guide Reference

Selection Policies

Reference

Description

Selection policies control the details of how selection techniques work. These policies are:

Basic policies
Policies that basically define the selection model. These include:

Count policy
Determines whether any number of elements can be selected or at most one.

Deselection policy
Determines whether and how all elements can be deselected by the user.

Contiguity policy
Determines whether all elements selected must be contiguous.

Technique initiation policy
When more than one technique is initiated by the same user action, determines which technique is used.

Modification policies
Policies that govern the details of how selections are modified. These include:

Adjustment policy
Determines how adjustment techniques affect the current selection region. There are three adjustment policies:

Reselect
Adjusts the previous selection relative to its anchor.

Enlarge
Enlarges the previous selection relative to its anchor.

Balance
Adjusts the previous selection relative to the end of the selection farthest from where the adjustment is being done.

Toggling policy
Determines the effect of toggling elements in a selection region. There are two toggling policies:

Independent
Each element added to the selection region has its state toggled, independently of the state of the other elements.

Anchor
When a new anchor element is determined, its state is toggled. All other elements in the selection region then take on the state of the anchor element.

Toggling removal policy
Determines the selection state of elements removed from a selection region that was adjusted using toggling. There are two toggling removal policies:

Revert
The elements removed revert to the selection state they were in prior to being included in the selection region.

Retoggle
The selection state of each element removed is set to the opposite of its state in the selection region.

Inclusion policies
Policies that determine which elements are included in a selection region. These include:

Area inclusion policy
When an area technique is used, determines which elements are considered to be in the selection region. Elements can be included in an area as follows:

Enclose
Only those elements that are entirely contained within the area.

Center
Any element whose center is within the area.

Touch
Any element completely or partially contained within the area.

Anchor inclusion policy
Determines whether to enlarge an adjusted selection region to include an anchor element or region.

End-point inclusion policy
When a selection technique is initiated or completed on an element, determines whether the selection region should be enlarged to include the element.

The following selection policies define selection model usage:

Count policy
Controls whether the user can select more than one element.

Deselection policy
Controls whether the user can deselect all elements.

Contiguity policy
Controls whether discontiguous selections are allowed.

Technique initiation policy
When more than one technique is initiated by the same user action, determines which technique is used.

The following selection policies define how selections can be modified:

Adjustment policies
Control how area and range selection techniques adjust the selection region. The policies are:

Reselect
Reselects the specified region according to the current boundaries.

Enlarge only
Enlarges the specified region to encompass the current selection.

Balance beam
Defines a balance point at the midpoint of the current selection. This is the standard policy for text.

Toggling policies
Control the kind of toggling in effect. The policies are:

Independent toggle
Independently toggles the selection state of each element in the selected region.

Anchor toggle
Identifies an anchor element to be the element nearest to the point at which the user pressed the SELECT button. This is the standard policy in the Motif implementation.

Toggle removal policies
When used with adjusted toggling, control what happens when elements are removed from the selection region. The policies are:

Revert
Reverts removed elements to the selection state they were in prior to being included in the selection region.

Retoggle
Toggles the selection state of removed elements.

The following selection policies define what is included in a selection:

Area inclusion policy
When an area technique is used, determines which elements are considered to be in the selection region. Elements can be included in an area as follows:

Enclose
Only those elements that are entirely contained within the area.

Center
Any element whose center is within the area.

Touch
Any element completely or partially contained within the area.

Anchor inclusion policy
Determines whether to enlarge an adjusted selection region to include an anchor element or region.

End-point inclusion policy
When a selection technique is initiated or completed on an element, determines whether the selection region should be enlarged to include the element.

Technique initiation policy
Controls whether an interaction initiates a touch swipe, area, or range technique.

Guidelines

Recommended
If a selection model's count policy allows the user to select any number of elements, the selection model should support one or more group techniques.

Required
If a selection model's count policy allows the user to select any number of elements and the user uses a selection technique in add mode or toggle mode, the selection state of elements outside the region identified by the technique should be unaffected.

Required
If a selection model's count policy allows at most one element to be selected, the selection model should not support group techniques.

Required
If a selection model's count policy allows at most one element to be selected, a technique that selects an element should deselect any other element that is currently selected.

Required
Allow the user to deselect all elements with mouse-based selection techniques when toggle mode is in use.

Required
Allow the user to deselect all elements with keyboard-based techniques or predefined action choices when add mode is in use.

Required
Allow the user to deselect all elements when a text or graphics cursor is in use.

Required
If the user is not allowed to deselect all elements, do not support add mode.

Recommended
If a selection model supports add mode or toggle mode, allow the user to deselect all elements.

Recommended
If a selection model supports only select mode and normal mode, do not allow the user to deselect all elements when an element cursor is in use.

Recommended
If the active cursor is an element cursor in a selection scope that allows any number of elements to be selected, but the cursor is not visible because an implicit focus policy is in use, allow the user to deselect all elements by using predefined action choices.

Required
If a selection model requires contiguity, the only group techniques that should be supported are those that select ranges of elements.

Required
If a selection model requires contiguity, it should not support use of toggle mode.

Required
Require contiguous selections only in text.

Recommended
Support discontiguous selections in any model whose count policy allows more than one element to be selected. In particular, support discontiguous selections in text if possible.

Recommended
If an application allows a user to choose between an area and range technique in a scope that contains primarily text, provide a value choice outside of the scope for this purpose.

Recommended
If an application allows a user to use both touch and area techniques in a scope:

  1. Use the touch technique when a mouse-based swipe technique is initiated on an element.

  2. Use the area technique when initiating any other selection operation (for example, mouse-based click on an element, any mouse-based operation initiated in the background, or any keyboard-based operation).

    3. Required
    Use a balance policy in linearly ordered selection scopes that consist entirely or primarily of text.

    Required
    Use an anchor toggling policy in text.

    Recommended
    Use an anchor toggling policy in all selection scopes.

    Required
    Use an enclose area inclusion policy.

    Required
    If the anchor point is on an anchor element (for example, after initiating a point technique or an area click technique on an element), extend the selection region to completely include the anchor element, unless a touch inclusion policy is in use.

    Required
    If an anchor region has been defined (for example, via use of a margin or multilevel selection technique), and a reselect adjustment policy is being used, extend the selection to include the anchor region.

    Required
    When a point technique or a group click (but not an adjust click) technique is initiated on an element, enlarge the selection region to include that element.

    Recommended
    When the elements in a selection scope are arranged in a regular one- or two-dimensional layout and the user initiates a new selection on an element, enlarge the selection region to include the element.

    Recommended
    When the elements in a selection scope are arranged in a regular one- or two-dimensional layout and the user completes a selection technique on an element, enlarge the selection region to include the element.

    Recommended
    When the elements in a selection scope are not densely packed together and the user initiates a new selection on an element, enlarge the selection region to include the element.

    Essential Related Topics

    For more information, see the Adjustment Techniques, Selection Modes, Selection Policies, and Selection Techniques reference pages.

    Supplemental Related Topics

    For more information, see the Margin Selection Techniques and Multilevel Selection Techniques reference pages.

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