A bit of an antique. The good old starcalcafter installing some other software in the system, there was a problem with closing (and saving the settings). After some troubleshooting it turned out that before the hang it sends a global SendMessage and some software won't respond. The solution is obvious - change SendMessage to PostMessage, not waiting for a response. You need to replace byte D9 with 69 at address 9887B.

And the whole folder starcalc, with plugins —

Measuring density

For my own memory. A variation of Archimedes' method for digital scales.
We need a beaker of water. We weigh first the object, then the beaker with water, then suspend the object on a string and lower it into the water so that it does not touch anything. The density of water is reasonably accurate unity, so:
Density = weight of object / (weight of beaker with water and object - weight of beaker with water)