I noticed some bugs in src/icons.h when I was tying to read the file with xpmtoppm.
The patch below fixes the icon data, but to work with xpmtoppm the word static should be removed from each definition and there should be a comment line /* XPM */ before each definition.
patch -ulbf src/icons.h << EOF
@@ -25,4 +25,4 @@
static const char * leaf_xpm[] = {
-"16 16 7 1",
-". c None",
+"16 16 6 1",
+" c None",
"+ c #000000",
@@ -51,3 +51,4 @@
"16 16 6 1",
-". c None",
+" c None",
+". c #AAAAAA",
"+ c #000000",
EOF