Handle of current object
h = gco
h = gco(figure_handle)
The current object is the last object clicked or selected via keyboard interaction, excluding uimenus. If the mouse click did not occur over a figure child object, the figure becomes the current object. The MATLAB® software stores the handle of the current object in the figure's CurrentObject property.
An object can become the current object as a result of pressing the space bar to invoke a callback in a dialog when a uicontrol in that dialog has focus (usually the result of using the Tab key to change focus).
The CurrentObject of the CurrentFigure does not always indicate the object whose callback is being executed. Interruptions of callbacks by other callbacks can change the CurrentObject or even the CurrentFigure. Some callbacks, such as CreateFcn and DeleteFcn, and uimenu Callback, intentionally do not update CurrentFigure or CurrentObject.
gcbo provides the only completely reliable way to retrieve the handle to the object whose callback is executing, at any point in the callback function, regardless of the type of callback or of any previous interruptions.