the text cursor's flash (blink) time in milliseconds
The flash time is the time required to display, invert and restore the caret display. Usually the text cursor is displayed for half the cursor flash time, then hidden for the same amount of time, but this may vary.
The default value on X11 is 1000 milliseconds. On Windows, the control panel value is used. Widgets should not cache this value since it may be changed at any time by the user changing the global desktop settings.
Note that on Microsoft Windows, setting this property sets the cursor flash time for all applications.