uiselectobject

ask the user to select an object of the specified type

UISELECTOBJECT ask the user to select an object of the specified type inside a figure and wait
until the user click on an object of the given type.
H = UISELECTOBJECT(TYPE,HFIG) waits until the user selects an object with
type equal to TYPE in figure HFIG and returns its handle. TYPE is a string or a cell
array of strings containing the valid types.
H = UISELECTOBJECT(TYPE) look for the specified object inside the
current figure.

Example:
h=uiselectobject('Line',gcf);
h.Color='r'