#87 Rework Export Dialog: Show loading process / Deuglify

[Sven Schrinner]

Exporting a big subset into an SDF file can take a lot of time. However, in the export dialog it is not visible, that the program is busy writing the subset into the file, until the user receives the dialog "Export successful".

There should also be a possibility to abort the export process (the dialog itself is not closable during the process) or at least the export dialog should not block the whole application.

[Till Schäfer]

Furthermore, the dialog is ugly in many ways:
- some labels are not properly aligned
- the layout changes when selecting csv or sdf (because of the different config options) in such a way that the comlete content of the dialog moves up. This is becuase the dialog is noting more than a stack of controls.
- it is not easy to select multiple properties. we should use a list here and not a collection of check boxes. than we can use control or shift to select multiple entries.
- i guess the code structure is also in a desolate state

=> We should redesign that dialog from the beginning and do it proper this time ;-)

[Till Schäfer]

i also dislike that the extension of the file cannot automatically added and the file selection dialog shout not just pop up after clicking export. I like it more to have a text filed, where i can type a path and reuse presious selected paths. than there might be an additional button to open the file chooser. The file chooser should have a reasonable default size. Now it so small, that i have to resize it every time.

[Sven Schrinner]

The export dialog was been completely reworked in commit [1a3ebe]. It is more structured and the file chooser is integrated in the dialog itself. After starting the export, a progress bar is shown. The export process can also be aborted at any time.

The file chooser always had a good size on my system, so I cannot see if it is still too small in your case, Till.