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Kevin Walzer, software developer.

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64-bit Tk-Cocoa and embracing limits

After releasing NameFind last month to mixed reviews, I am now knee-deep in updating my applications to work as 64-bit programs under Tk-Cocoa.

I'm finding some pleasant surprises. Many minor interface glitches and performance problems that persisted under Tk-Carbon have magically disappeared under Tk-Cocoa. Some users, for instance, complained about slow scrolling and image redraw in NameFind, which draws a lot of images in its tableview. The higher performance of 64-bit seems to have fixed this problem. Similarly, the broken help menu search function in Tk-Carbon now works as expected in Tk-Cocoa.

I'm also finding some knottier issues that Tk-Cocoa can't magically fix. A couple of reviewers of NameFind complained about the way its toolbar is laid out. Doesn't look native, they grumbled. They're right. It's a custom Tk-based toolbar widget that tries to imitate the Cocoa-style toolbar--not very well, in their view.

This is actually a very hard problem to solve. The "unified toolbar" style that started with Cocoa applications and is now very prevalent on the Mac is not easy to implement in Tk. I've tried patching Tk at the C-level to draw a metal-style, textured window in a way that integrates well with Tk--but it has major problems with screen redraw, flickering when the window's resized, and so on. It looks good at first, but induces more and more nausea as you go on. So I've abandoned metal windows.

I'm starting to come to terms with the fact that even as Tk is now a 64-bit-capable, Cocoa-based GUI toolkit, thanks to Daniel Steffen's hard work, Tk still doesn't entirely fit in to Mac UI fashions, and perhaps never will. A huge amount of work I've done over the past few years has been fueled by my insecurity about this issue. Perhaps it's time to stop worrying about this issue altogether. It focuses on Tk's limitations, rather than playing to Tk's strengths--it's a powerful toolkit for rapid development. Its customizability means one can go a long way toward making it fit in with its platform, but it does have limits.

I'm wondering if, instead of trying to emulate the UI fashion of the week on the Mac, I should focus on following the best practices of the leading commercial Tcl/Tk application developer, ActiveState. ActiveState makes developer tools for scripting languages, and targets Windows, Unix/Linux, and OS X. It makes extensive use of Tk in its applications, some of which cost several hundred dollars.

Here's a screenshot from the Mac version of an ActiveState product, the Perl Dev Kit, which uses a Tk GUI:

Looking at this, you'll see that this application has a very polished user interface, and one that fits in fairly well on OS X. It uses native widgets in its table display--the discolosure triangle, the Aqua column headers, the system shading in the window, and so on. It also uses native buttons in the toolbar. The toolbar itself isn't native, but does it really look that out of place? Having played with a demo version of this application, I think it's quite professional, and does not feel out of place at all.

I've spent years trying to work around the fact that Tk isn't completely native on the Mac. Striving to fit in with the platform has yielded fruitful results. In general, the UI polish of my apps has greatly improved. Incorporating user feedback has helped improve the usability of my programs. Paying closer attention to these issues has also allowed me to contribute feedback and even code to Tk's core on the Mac, where the native platform integration takes place--and where improvements in the integration pay the biggest dividends. I will continue to do this as time allows; I have some open-source projects on my plate for later this year that will continue my work along this path.

But I have to wonder: does the toolbar in NameFind really look better than the toolbar in the ActiveState application?

I used to think so; I've spent a lot of time trying to achieve the "iconbutton" look of the Cocoa toolbar, in which just the image darkens. But now I'm not so sure. Perhaps my time might have been better spent in adding features that would really make my programs unique. A basic "button bar" would have taken much less time, much less trial and error, and, as the ActiveState application shows, would have looked no less professional.

As I get closer to releasing a 64-bit version of NameFind, and bringing the rest of my applications to the 64-bit Tk-Cocoa foundation, I'm leaning toward leveraging Tk's strengths for rapid development of a polished user interface, and not worrying so much about where it doesn't perfectly integrate with OS X.

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