I can tell you from experience why Java is so difficult to do a desktop app. The create a winform in Java you need to use a library called Swing. This gives you access to UI controls.

Here's a sample scenario, sorry if I loose you. I get lost doing this all the time:

Create a frame (this gets assigned a size)
Create a panel and add it to the frame
- Within the panel you define a layout. The layout specifies how controls get drawn in the panel. You can have multiple panels in 1 frame. I'm working in an Invoice form right now. It has a Gridbaglayout panel in the top part for the data entry controls. And a Flow layout panel in the bottom part for the buttons.
- You can define sizes for the controls. Like the buttons in the above example. But there's no stopping the JVM from resizing if it thinks it knows more then you.
- The Gridbaglayout, as above, adds many properties that must be defined for the controls. These properties define how the controls will be spaced, how they will resize themselves if the form is resized, etc. It's a real joy to set these properties then run the form to see what you've just done looks like. Since there's no Wysiwyg.

This isn't necessarily due to the lowest common denominator. But to allow the JVM to create similar looking forms on different platforms.

However, even within the Java community there's unrest over Swing. Sun has done little to update it since the library was first created. In Java 1.2 I believe. I followed thru some blog sites just last weekend where Java guys were bemoaning the state of Swing. Some thought there are new technologies that could help make Swing development more inticing. There were just as many who thought the way Swing is designed would prohibit making it work acceptably. This includes both making it a more efficient tool, and making it easier for developers to work with.

>The biggest crossplatform issues I've seen are with UI. You have to design for the lowest common denominator. So, the app looks crappy everywhere. I've talked to several people who have done extensive work on Java and .Net and they tell me Java is just plain difficult to do anything while .Net is pretty easy in comparison.
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>>Last I checked, Java is used a whole bunch (not that I'm a Java fan or anything). So what's your take . . . don't try crossplatform because it has failed (in some people's opinions, at least) in the past? VFP used to be crossplatform and many of those who programmed that way were not happy to see it dropped. I'm not using RealBasic, yet, but one of our users group members has been working with it and likes it. I was just mentioning some possibilities, that's all . . .