File chooser improvements

[mgarin]

Current JFileChooser implementation has a set of issues that need to be resolved.

Bugs

• File chooser current directory issues #10
• JFileChooser's dialogTypes behave different for WebLAF and the standard LaFs. #215
• JFileChooser file filters issues #278
• File chooser - saved file name filtering #290
• FileChooser - cannot drag-and-drop files from the Finder (macOS) #600

Initialization speed improvements

• File chooser creation is quite slow #140
• WebFileChooser for file tree #227

Other improvements

• File Chooser: scrollbars have small block increment #162
• File Chooser: keyboard navigation #163
• Drag & dropping folder onto the chooser should select it instead of navigating to it if in "directories only" mode

New features

• Add desktop icon in WebFileChooser dialog #206
• FileChooser tree with specific directory as root #255
• FileChooser - give it a more "native" feel #311

My original plan was to rework file chooser once project is moved to Java 8+ (or even later one) to incorporate all the NIO improvements, but this might take a long while to get to. So it would be more reasonable to simply rework it at the current project stage and then improve it a bit further after the minimum supported Java version is increased.

Currently I'm planning to work on this in v1.2.15 update, so before the major changes in v1.3.0.

[Sciss]

If I may add another tiny improvement: If the dialog is set to select directories - FileSelectionMode.directoriesOnly - I think it's useful to select a directory dropped from the desktop manager, instead of branching into that directory. I have implemented it this way: https://github.com/Sciss/Submin/blob/main/src/main/java/de/sciss/submin/SubminFileChooserPanel.java#L138 (additional check getFileSelectionMode)

[mgarin]

@Sciss That's a good point, I'll throw it onto the list.

[mgarin]

I've already done some sketches of the rework locally before so I have the general idea how it should be done, just never really got far into the implementation.

The general goal was and still is to make no compromises - file chooser needs to have clean code, be fully styleable, asynchronous, configurable and easily modifiable in the future. Something akin to the JTabbedPane rework I've finished a while ago. That will ensure that future fixes and improvements can easily be added on top of existing implementation without breaking random things.

So if you have any other ideas on possible improvements (even any crazy ones) - feel free to throw them in here. Current chooser was written years ago and library features were way more limited back at the time, there are definitely a lot of things that can be improved now, even with Java 6 support.