Features request (Tabbar changing tab event and more customization - ProgressBar indeterminate)

[ahmed-abdelrazek]

1- Tabbar event for changing tab with option to cancel that trigger before the changed event
2- Tabbar property to change tab corner radius and selected tab background color
3- ProgressBar indeterminate property like wpf
4- Titlebar option to make round the corners (for windows 10 like 11)