You can call InstallPopup() to display the panel, GetUserEvent() to wait for the panel, and RemovePopup(0) to remove it.
InstallPopup() displays and activates a panel as a modal dialog box. You can't operate controls on any other panel in the same thread. You need to call LoadPanel on the panel before calling InstallPopup.
GetUserEvent(), with the wait mode set True, will wait for a commit event to be generated. It returns the control ID. If you want to continue only on EVENT_COMMIT from a certain control, you can call GetUserEvent in a loop until the control ID matches the one you want. Since InstallPopup sets the popped-up panel to be modal, you will only get EVENT_COMMITs from the popup panel.
RemovePopup(0) removes the active popup.