On-Screen Takeoff uses a database to store all information, and some changes (those made in dialog boxes that "pop-up", typically) aren't saved immediately. These changes are not saved until you click the "Apply" button or close a dialog box by clicking the "OK" button. For example, if you are adding a Condition, the Condition is not saved until you click the "Apply" or "OK" button.
Notable exceptions:
- Deleting Conditions, Typical Groups, and Zones is immediate and permanent (there's no undoing deleting a Condition).
- Deleting takeoff, Typical Group Frames, drawn Zones, and Annotation is immediate, although 'undoable' until you navigate away from the Page.
- Deleting an Alternate or Change Order is immediate and permanent, child Bids are not stored in the "Deleted Bids" folder.
- Creating a Bid - when you start creating a Bid, it is assigned the next Bid Number available and the Bid No. field in Tools > Options > New Bid is incremented. Even if you cancel out of creating this Bid, the Bid Number assigned is "burned" and will not be used again (unless you manually change the filed in Tools > Options > New Bid).
Different Dialog Box Types
Dialog boxes may be "OK" or "Select/Cancel" types, depending on how they were opened.
Select Dialog Boxes
For example, when a user clicks on the Lookup button 
for a field (such as when assigning a Employee as Estimator for a Bid), a "Select/Cancel" dialog box opens.
example of the Employee dialog box showing "Select" and "Cancel"
Select dialog boxes open a Master List so the user can select some existing record to insert some field in a bid or another Master Record (such as adding Condition Type to a saved Condition Style). In the Select dialog box, you also can create a new record, change or delete an existing record, print the list, or even (Employees, for example) import records from a CSV file.
OKDialog Boxes
When there is no choice possible (when opening the Employees dialog box from the Master Menu) only an "OK" button is shown.
example of the Employee dialog box opened from the Master menu, showing "OK"
OK dialog boxes are shown when the user is only managing records, not inserting a record into a bid.
When editing
database tables, avoid adding, then deleting or modifying records, then adding/deleting more within a dialog box without saving the changes. For example, when adding Bid Areas, it is best to add all the Areas required and close the dialog, then if changes are needed, re-open the dialog box, make the changes and close it again. (Do not add, then delete, then add more without clicking the OK button between changes.)
Getting Around OST - Shortcuts