Design / Code: ListBox populated in a different window [API1]

In a user’s populated window, I have a ListBox.

I can actually populate it using Paste / Drag and Drop and modify it by DoubleClick.

I wanted to modify it to display a brand new way to populate it: open another window wth buttons to Open (a text file), Save (in a text file), Add via Paste, etc.

I discovered that DoubleClick (in the original/master Window) does works only when issued in a Row…
I wanted to use it to display the Edit Window.
Nota: I loved to be able to edit on DoubleClick :wink:

What I’ve done so far:
a. I changed the Edit way in the original window (it was done via the DoubleClick Event).

b. I call the multi-purpose new Window in the DoubleClick Event (and this does not works).

c. I added the “ multi-purpose new Window” with code to Open (populate the ListBox) and Save (from the ListBox) Text file.

d. Add simple code to copy that ListBox contents into the main one.

Now, I do not have idea to how to display that window. Adding a button was my first idea, but I do not had room for it (thus the new window to easy the text adding job).

The whole is saved into a SQLite DB…

To be complete, I also have a TextField (or TextArea) to put comments in.

The whole window is a data entering system: you put title, number, company, etc. (in some TextFields) plus a simple table of contents (ListBox), a Comments TextField (or TextArea) for Comments. A Canvas is also provided for Cover (Magazine / Book / Video / else).

More windows exists. I would split the data feeding into more windows, but I feel this will make the whole user experience complex beyond needs.

Idea(s) ?