GtkAdjustment a #GtkObject representing an adjustable bounded value. The #GtkAdjustment object represents a value which has an associated lower and upper bound, together with step and page increments, and a page size. It is used within several GTK+ widgets, including #GtkSpinButton, #GtkViewport, and #GtkRange (which is a base class for #GtkHScrollbar, #GtkVScrollbar, #GtkHScale, and #GtkVScale). The #GtkAdjustment object does not update the value itself. Instead it is left up to the owner of the #GtkAdjustment to control the value. The owner of the #GtkAdjustment typically calls the gtk_adjustment_value_changed() and gtk_adjustment_changed() functions after changing the value and its bounds. This results in the emission of the "value_changed" or "changed" signal respectively. The #GtkAdjustment-struct struct contains the following fields. #gfloat lower; the minimum value. #gfloat upper; the maximum value. #gfloat value; the current value. #gfloat step_increment; the increment to use to make minor changes to the value. In a #GtkScrollbar this increment is used when the mouse is clicked on the arrows at the top and bottom of the scrollbar, to scroll by a small amount. #gfloat page_increment; the increment to use to make major changes to the value. In a #GtkScrollbar this increment is used when the mouse is clicked in the trough, to scroll by a large amount. #gfloat page_size; the page size. In a #GtkScrollbar this is the size of the area which is currently visible. Creates a new #GtkAdjustment. @value: the initial value. @lower: the minimum value. @upper: the maximum value. @step_increment: the step increment. @page_increment: the page increment. @page_size: the page size. @Returns: a new #GtkAdjustment. Sets the #GtkAdjustment value. @adjustment: a #GtkAdjustment. @value: the new value. Updates the #GtkAdjustment @value to ensure that the range between @lower and @upper is in the current page (i.e. between @value and @value + @page_size). If the range is larger than the page size, then only the start of it will be in the current page. A "changed" signal will be emitted if the value is changed. @adjustment: a #GtkAdjustment. @lower: the lower value. @upper: the upper value. Emits a "changed" signal from the #GtkAdjustment. This is typically called by the owner of the #GtkAdjustment after it has changed any of the #GtkAdjustment fields other than the value. @adjustment: Emits a "value_changed" signal from the #GtkAdjusmtent. This is typically called by the owner of the #GtkAdjustment after it has changed the #GtkAdjustment value field. @adjustment: Emitted when one or more of the #GtkAdjustment fields have been changed, other than the value field. @adjustment: the object which received the signal. Emitted when the #GtkAdjustment value field has been changed. @adjustment: the object which received the signal.