C# – FileUpload.PostedFile always null inside UpdatePanel

There is actually a (subtle) difference between the two. Imagine you have the following code in File1.cs:

// File1.cs
using System;
namespace Outer.Inner
{
    class Foo
    {
        static void Bar()
        {
            double d = Math.PI;
        }
    }
}

Now imagine that someone adds another file (File2.cs) to the project that looks like this:

// File2.cs
namespace Outer
{
    class Math
    {
    }
}

The compiler searches Outer before looking at those using directives outside the namespace, so it finds Outer.Math instead of System.Math. Unfortunately (or perhaps fortunately?), Outer.Math has no PI member, so File1 is now broken.

This changes if you put the using inside your namespace declaration, as follows:

// File1b.cs
namespace Outer.Inner
{
    using System;
    class Foo
    {
        static void Bar()
        {
            double d = Math.PI;
        }
    }
}

Now the compiler searches System before searching Outer, finds System.Math, and all is well.

Some would argue that Math might be a bad name for a user-defined class, since there's already one in System; the point here is just that there is a difference, and it affects the maintainability of your code.

It's also interesting to note what happens if Foo is in namespace Outer, rather than Outer.Inner. In that case, adding Outer.Math in File2 breaks File1 regardless of where the using goes. This implies that the compiler searches the innermost enclosing namespace before it looks at any using directive.

To execute the init everytime the UpdatePanel changes you need to register the script using ScriptManager:

// control is your UpdatePanel
ScriptManager.RegisterStartupScript(control, control.GetType(), control.UniqueID, "your_tinymce_initfunc();", true);

NOTE: You cannot use exact mode on your init function, you can use either textareas or a class selector, or else it won't work properly.

You also have to use

ScriptManager.RegisterOnSubmitStatement(this, this.GetType(), "", "tinyMCE.triggerSave();");

On a postback of a UpdatePanel the editor content isn't saved on the Textbox, because the default behavior is only for form.submit, so when you submit anything it will save the text before it posts.

On the code behind to get the value you will just need to access TextBox.Text property.

NOTE: If you are using the .NET GZipped you probably will have to drop it, I couldn't get it working, I had to remove this completely.