changed
The "changed" signal is emitted when any of the properties other than the value is altered in a GtkAdjustment. This happens when the adjustment object has its values initialised or unset, or when a widget-owned scrollable object is resized, or when the adjustable widget has a configure() method and calls it.
Note that a "value-changed" signal is also emitted under the same circumstances, regardless of whether the value itself has been changed.
Callback function
void callback(GtkAdjustment button);
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