You can edit the themes color for the ThumCal according to your like. You just need to know what kind of colors u want for your ThumbCal.
Where is ThumbCal Skins store?
ThumbCal Skins is store in USER\Program Files\ThumbCal\
where USER is the location u install like My Device or My Storage or Storage Card
Skin file is normally a zip file and name like skin.ThumbCal Black.zip
This zip contains the skin.ini and the images used.
Editing the Color Used in Theme
Every theme file comes in zip format will have the skin.ini. and the background images. You can edit the skin.ini for the color used in the themes.
EG colorBorder=#D9D9D9
#D9DD9D9 is the color code, change it to the color code u like.
Use this website to test the color combinations you want to use for your ThumbCal.
Color Combinations>>>
Code for skin.ini(no background images)
[styles.calendar]
colorBorder=#D9D9D9
colorGrid=#222222
colorYearMonthBarBg=#6495ED
colorYearMonthBarText=#ffffff
colorYearMonthBarButtons=#B0C4DE
colorDayBarBg=#D9D9D9
colorDayBarText=#000033
colorDayGridText=#22316C
colorDayGridBg=#F8F8FF
colorDayGridBgSelected=#B0C4DE
colorDayGridBorderToday=#499DF5
colorDayGridTextSelected=#ffffff
colorAppointmentIndicator=#6495ED
[styles.contextmenu]
colorBorder=#003F87
colorBg=#6495ED
colorText=#eeeeee
colorTextSelected=#003F87
colorSelectionMark=#dddddd
[styles.detailview]
colorBorder=#bbbbbb
colorBg=#B0C4DE
colorBg2=#6495ED
colorText=#ffffff
colorTextSelected=#000033
colorSelectionMark=#ffffff
[styles.statusbar]
colorBg=#506987
colorBgGradient=#B0C4DE
colorText=#eeeeee
colorMeters=#eeeeee
colorTextShadow=#000000
colorMetersShadow=#000000