As explained in one of my previous blog posts where I revamped the unresponsive window dialog, KWin isn’t really designed to show regular desktop windows of its own. It instead relies on helper programs to display messages. In case of the “no border” hint, it just launched kdialog, a small utility for displaying various message boxes from shell scripts. This however came with a couple of caveats that have all been addressed now:

First of all, the dialog wasn’t attached to the window that provoked it. When the window was closed, minimized, or its border manually restored, it remained until manually dismissed. Secondly, it said “KDialog” and used a generic window icon (that would have been an easy fix of course). Further, the user might not even have kdialog installed which actually was the case on KDE Linux until very recently. Ultimately and most importantly, it told you that you were screwed if you didn’t have a keyboard but didn’t offer and help if you really went without one. I therefore added an option to restore the border right from the dialog. Should you have a dedicated global shortcut configured for this action, it will also be mentioned in the dialog.
The dialog when manually setting a window full-screen has similarly been overhauled, including an undo option. While at it, I removed the last remaining code calling kdialog, too: the “Alt+tab switcher is broken” message. It is now a proper KNotification. Something you should never see, of course.
Another dialog that I gave some attention was the prompt when copying a file would overwrite its destination. If you have Kompare installed and copy a plain text file (that includes scripts, source code, and so on), the dialog displays a “Compare Files” button. It already guesstimated whether the files are similar but now you can actually see it for yourself.

KIO’s PreviewJob that asynchronously generates a file preview now provides the result of its internal stat call, too. This means that once you receive the preview, you also get the file’s properties, such as size, modified time, and file type basically for free. The rename dialog then displays this information in case it wasn’t provided by the application already. Dolphin now also makes use of this information while browsing a folder which should improve responsiveness when browsing NFS and similarly mounted network shares. At least when previews are enabled, it no longer determines file types synchronously in most scenarios.
Since the rename dialog is able to fetch file information on demand, Ark, KDE’s archiver tool, rewrites the source URL it displays in the dialog to a zip:/ URL (or tar:/ or whatever supported archive type). This way the dialog can display a preview transparently through the Archive KIO worker which also gained the ability to determine a file’s type from its contents. In case you didn’t know, you can configure Dolphin to open archives like regular folders.
Finally, most labels in KIO that show the mtime/ctime/atime no longer include the time zone unless it is different from the system time zone. Showing “Central European Standard Time” in full after every date was a bit silly. Unfortunately, QLocale isn’t very flexible and only knows “short” (19:00) or “long” (19:00:00 Central European Standard Time) formats. You can’t explicitly tell it to generate a time string with seconds, or with 12/24 hour clock, or a date with weekday but no year, and unfortunately the “long” time format includes the full time zone name.
Thanks for this! However, as with the previous post of yours, it would be great if Kompare was not hardcoded but instead there was a way to query the system for a default diff application and use that.
if there were a way to query for a “compare application” then sure.
We could perhaps invent a mime type `application/x-kde-diff-tool` or something that an application can then specify as supported.
yeah, something like that I imagined. Though I hope to be able to use Meld for it – not sure if the KDE suffix is needed? (Meld is about the only non-KDE app I am still using.)
That sounds like it would be a nice fit for the upcoming™ XDG Intents specification. It would be especially cool if you could set different diff applications for different mime types, so that you could e.g. have something based on Mergiraf for source code, or a custom app for image files, etc.
There is a “default apps” in the kde configuration dialog, maybe add another entry there?
All of those entries rely on proper file types or URL handlers. There is no such thing for comparing files (yet).