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>Range Widgets

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>Range Widgets

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>The category of range widgets includes the ubiquitous scrollbar widget

and the less common scale widget. Though these two types of widgets

are generally used for different purposes, they are quite similar in

function and implementation. All range widgets share a set of common

graphic elements, each of which has its own X window and receives

events. They all contain a "trough" and a "slider" (what is sometimes

called a "thumbwheel" in other GUI environments). Dragging the slider

with the pointer moves it back and forth within the trough, while

clicking in the trough advances the slider towards the location of the

click, either completely, or by a designated amount, depending on

which mouse button is used.

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>As mentioned in 

HREF="c563.html"

>Adjustments

> above,

all range widgets are associated with an adjustment object, from which

they calculate the length of the slider and its position within the

trough. When the user manipulates the slider, the range widget will

change the value of the adjustment.

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>Scrollbar Widgets

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>These are your standard, run-of-the-mill scrollbars. These should be

used only for scrolling some other widget, such as a list, a text box,

or a viewport (and it's generally easier to use the scrolled window

widget in most cases).  For other purposes, you should use scale

widgets, as they are friendlier and more featureful.

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>There are separate types for horizontal and vertical scrollbars.

There really isn't much to say about these. You create them with the

following functions:

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>GtkWidget *gtk_hscrollbar_new( GtkAdjustment *adjustment );

GtkWidget *gtk_vscrollbar_new( GtkAdjustment *adjustment );

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>and that's about it (if you don't believe me, look in the header

files!).  The 

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>adjustment

> argument can either be a pointer to an

existing Adjustment, or NULL, in which case one will be created for

you. Specifying NULL might actually be useful in this case, if you

wish to pass the newly-created adjustment to the constructor function

of some other widget which will configure it for you, such as a text

widget.

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