void SetProp(int ID, int Value);
If You use Memo.CurrPar usually only the current paragraph, the paragraph the cursor is in, will be modified. Certain methods can also modify all selected paragraphs. To use this feature You first need to call SetProp with ID=1 and Parameter=1 to initialize the list of selected paragraphs. When done please don't forget to call SetProp with ID=1 and Value=0 to clear the list. If not text was selected, at least the current paragraph will be added to the internal list.
Add the current paragraph to the internal paragraph list (value is ignored). You need to call SetProp(1,0) to switch the "paragraph list" mode off.