The following popups are supported for recording and replaying in Silk Performer 2011:

JavaScript Alert/Prompt/Confirm dialogs
These dialogs can be interacted with during record and replay for simple workflows.  For example, a JavaScript dialog which appears during form submission (missing required data) will appear and a BrowserDlgSetButton will be scripted which represents which button was pressed and then a BrowserDlgStop function will be scripted to close the dialog. 

Clicking the OK button is scripted as:

Win32 Dialogs 

Win32 dialogs such as Print.  These dialogs are handled using the BrowserDlgSetButton - to record the button which the user pressed during record and BrowserDlgStop - which closes the dialog.  It is important to note that these actions are usually clientside actions which means they do not have any bearing on a loadtest and so recording a print command would not offer anything to the test.  Additionally, these actions can sometimes load other objects which there would not be support for - for example, the Print Preview option loads a process separate to the Browser Application which the Browser Application will not recognize. 

On replay, the Print dialog may or may not appear (depending on how it gets triggered).  If it does appear then the BrowserDlgStop function will close it and if it does not appear then the BrowserDlgStop function will return a positive result so as not to generate unnecessary errors during a loadtest. 

File Download Dialogs

File Download Dialogs are recognized and the BrowserFileDownload function is scripted.   BrowserFileDownload is a recent addition to the Browser Driven API and can be used for downloading a file at a specific location.  In addition the button presses for the Save As dialog which the browser prompts are scripted with a BrowserDlgSetButton and BrowserDlgStop.

Internet Explorer Shortcuts

Open in new window and open in new tab functionality is supported.  Currently both actions are treated as open in new tab actions and a new tab is opened in the Browser Application.  This appears in the script as BrowserGetActiveWindow which traces the new tab and and BrowserNavigate which handles navigation to the requested URL once the new tab is active.

Currently the following is not supported:

Cascaded JavaScript dialogs - this is when an action against a JavaScript dialog opens another JavaScript dialog.  The first dialog may be recognized but the second dialog will not be. 

The JavaScript popup functions showModalDialog() and showModelessDialog() are also not currently supported as these open and exists outside of the BrowserApplication.

The Browser Driven Load Testing functionality is being enhanced frequently and any unhandled or poorly handled dialogs you encounter should be logged to support for analysis.  It may be possible in some situations to consider adding support for a particular dialog in a future version of Silk Performer or there may be an alternative solution available.