Added a fourth dark mode option on Windows: Disabled, Basic, Full, Forced. Disabled (0) forces dark mode off on Mac and Windows. Enabled (1) System decides but only window frame is dark mode on Windows. Full (2) System decides but everything that can be dark is on Mac and Windows. Forced (3) Force dark mode on Mac and Windows regardless of system setting. Enabled (1) and Full (2) are identical on Mac. Added code to enable full dark mode in the test program. Several widgets are not able to go dark on Windows currently: Notebook, Menubar

--- a/dwtest.c	Thu Jun 11 22:21:53 2020 +0000
+++ b/dwtest.c	Fri Jun 12 20:40:47 2020 +0000
@@ -1794,6 +1794,9 @@
     ULONG notebookpage9;
     DWFEATURE feat;
 
+    /* Enable full dark mode on platforms that support it */
+    dw_feature_set(DW_FEATURE_DARK_MODE, 2);
+
     /* Initialize the Dynamic Windows engine */
     dw_init(TRUE, argc, argv);