c# - Disable Alt+F4 in UserControl -

i have user control , want disable alt + f4 oportunity end user. when user control shows, there opportunity close alt + f4, program goes base class in method:

protected override void onclosing(system.componentmodel.canceleventargs e) {     //content = null; // remove child logical parent - reusing purposes     this.removelogicalchild(content); //this works faster     base.onclosing(e);     { gc.collect(); }; } 

what must here or somewhere else, disable user control closing on alt + f4?

to sure, question best practice. however, if want this, need prevent window containing usercontrol closing.

the easiest way set dependencyproperty on usercontrol boolean flags whether container can closed. set true when want close (you have button or using close control).

public boolean allowclose {     { return (boolean)getvalue(allowcloseproperty); }     set { setvalue(allowcloseproperty, value); } }   public static readonly dependencyproperty allowcloseproperty =     dependencyproperty.register("allowclose", typeof(boolean),      typeof(myusercontrol), new uipropertymetadata(false)); 

then, in windows closing event, check property set true. if not, set e.cancel = true;

using example:

   protected override void onclosing(system.componentmodel.canceleventargs e)    {     if (! myusercontrol.allowclose)     {         messagebox.show("even though windows allow alt-f4 close, i'm not letting you!");         e.cancel = true;     }     else     {         //content = null; // remove child parent - reuse         this.removelogicalchild(content); //this works faster         base.onclosing(e);         { gc.collect(); };     } }