Aptana Studio 3 / Eclipse : strange different widths for tabs/spaces in PHP editor?

Somehow in a PHP editor in Aptana Studio 3 I get very strange behaviour of spaces before indented lines.

The spaces seem to change in width (!) after you type them. Even with a monospace font the text columns are not aligned.

For example :

Both lines in this example have 8 spaces before the text, but they are aligned differently !

What could cause t开发者_运维知识库his? I tried every setting in Aptana to fix this, but I can't solve the problem.

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Found the solution:

I was using the Aptana Studio 2.x theme. Changed it to Eclipse theme and the editor works like it should...

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Here's the solution I found:

Go to Preferences > Aptana Studio > Themes. In the element list, find "punctuation", then deselect "B"(bold). That should fix the problem.