New Comparison

One dialog says what is being compared with what. It shows every path at once, takes them by typing, browsing or dropping, lets any two rows be swapped, offers the comparisons you made before, and says what is wrong with a choice before it runs anything. Open it with File ▸ New Comparison or Compare ▸ New Comparison (Ctrl+N), or New on the tool bar. Ways to open a comparison sets it beside the other routes.

What you are comparing

Two buttons across the top decide how many paths the dialog asks for and what it does with them:

Choice	What it takes	What opens
Two-way comparison	Old and New, as source files, library objects, or two whole libraries.	A File Compare; two whole libraries open a Compare Summary.
Three-way merge	File1, Base and File2.	A three-way merge.

The third path appears only for a three-way merge; the dialog grows a row rather than showing an empty one the rest of the time.

Giving it the paths

In a two-way comparison, Old is the reference: results are phrased as what happened to it. Each slot can be filled in these ways:

Type or paste into the box. It is an ordinary text box, so a path copied out of Explorer or a build log goes straight in.
Browse… opens a file dialog for that side. It accepts a supported source file or a PowerBuilder library.
Object… appears beside a slot only while it names a library, and chooses one source object from it: see Select PB Object. With source files there is no Object button.
Drop files anywhere on the dialog. Two at once fill both sides in the order they came; three in three-way mode fill all three. One on its own fills whichever side is still empty, and when both are full it replaces Old, which is what correcting a mistake looks like.

The button with the two arrows between two rows swaps those two, as the stops of a route are swapped in a map: between Old and New in a two-way comparison, and in a merge one between File1 and the Base and one between the Base and File2, so the Base can be put in the middle whatever order a drop or a browse left the three files in. Its tool tip names the two rows it swaps.

Recent

The comparisons you have already made are listed under the paths, most recent first: in Two-way comparison the pairs, in Three-way merge the merges. Double-click one to fill the slots from it, each file in its role. The list is the same as File ▸ Recent, which also holds folder pairs and saved selections; it keeps fifteen comparisons, the five latest merges among them whatever came after, and survives closing the application. Clear Recent List, at the bottom of File ▸ Recent, empties it.

Before the compare runs

The dialog states its objection while the choice is being made rather than failing afterwards. Compare stays disabled until there is nothing to object to.

Objection	Cause
There is no file at path.	A path was typed wrongly, or the file has moved.
Choose source files throughout or choose objects from PowerBuilder libraries throughout.	The dialog holds a source file and a library object together.
Select an object for every library slot before comparing.	One slot still names a whole library while the comparison requires objects.
The files are of different types.	A window against a DataWindow, for example. Objects of different types do not compare meaningfully, so the dialog rejects them in both two-way and three-way comparisons.

The dialog takes files: a source file, a library, or an entry of a library. A folder is not one of them, and naming one gets There is no file at path. Two folders of exports, two PowerBuilder 2025 Solution folders or two of their PBL folders are compared from a File Selection, which expands a folder into the objects beneath it, by dropping the two folders on the window, or by naming them on the command line. A File Selection is also the place for more than one pair.