How to set Mixer Brush to use "Load Solid Colors Only" by default?

here's a JSX script that selects the mixer brush and activates "Load Solid Colors Only".  you can place it in your plugins folder and assign a shortcut to it.

// Select Mixer Brush Tool
var idslct = stringIDToTypeID("select");
var desc1 = new ActionDescriptor();
var ref1 = new ActionReference();
ref1.putClass(stringIDToTypeID("wetBrushTool"));
desc1.putReference(stringIDToTypeID("target"), ref1);
executeAction(idslct, desc1, DialogModes.NO);
// Turn ON "Load Solid Colors Only"
var ps = app;
var ref2 = new ActionReference();
ref2.putProperty(stringIDToTypeID("property"), stringIDToTypeID("currentToolOptions"));
ref2.putEnumerated(stringIDToTypeID("application"), stringIDToTypeID("ordinal"), stringIDToTypeID("targetEnum"));
var toolDesc = executeActionGet(ref2);

var opts = toolDesc.getObjectValue(stringIDToTypeID("currentToolOptions"));
opts.putBoolean(stringIDToTypeID("loadSolidColorOnly"), true);

var desc2 = new ActionDescriptor();
var ref3 = new ActionReference();
ref3.putClass(stringIDToTypeID("wetBrushTool"));
desc2.putReference(stringIDToTypeID("target"), ref3);
desc2.putObject(stringIDToTypeID("to"), stringIDToTypeID("currentToolOptions"), opts);
executeAction(stringIDToTypeID("set"), desc2, DialogModes.NO);

You shouldn't have to - that is a sticky feature that should remain selected even after changing brushes, tool, documents or quitting the application.