Hijri Tray Applet for GNOME (also works with KDE) that uses Hijra Algorithm by Muayyad Saleh Alsadi provided by python-hijra package.

This algorithm is based on integer operations which that there is no round errors (given accurate coefficients) the accuracy of this algorithm is based on 3 constants (p, q and a) where p/q is the full months percentage [ gcd(p,q) must be 1 ] currently it is set to 191/360 which mean that there is 191 months having 30 days in a span of 360 years, other months are 29 days, and a is just a shift.