This option is available from the "Insert | HtmlHelp Control" menu and is a HtmlHelp specific option. This option is rarely used because of a quirk in HtmlHelp v1, it can affect how your help file is redrawn, i.e. the screen redraws are patchy. But some use it and it is included for comprehensiveness.

Adding a Splash Screen means that when the Topic you have added it to is opened a bitmap will be displayed for a specified number of seconds.

Splash Screen Tutorial

1. Choose the Topic that will be opened first. There is a setting in "HtmlHelp Compiler Options" for the Default Topic. Click anywhere in this Topic.
2. Select "Insert | HtmlHelp Control | Splash Screen" and the Splash options will appear
3. Use the ellipsis button to select a bitmap, not a jpg or gif. Only bitmaps are supported for Splash screens in HtmlHelp v1. The bitmap will be copied to your HtmlHelp folder, not your Images folder as you might expect. And, when you ship your CHM file, you will need to ship your bitmap file with it and install it in the same folder as your CHM file.
4. Now set the delay. This is the number of seconds, 1 to 30, that your bitmap will be displayed for, before it is automatically closed.
5. Click [OK], now compile and test.