Modal dialog box on user control

Question

Hello all,

My requirement is, popup modal dialog box on performing action on a user control and it should block only the user control instead of main window.
For ex, MainWindow has a TabControl with many tab items and each tab item has a custom UserControl. On performing actions on a usercontrol(Belongs to a tab ), modal dialog box shall be displayed.But this dialog box should not block user from clicking on other controls like other tab item or some other control.
So how can we restrict the modality of dialog box?
Pls let me know ur input

Thanks.