I've asked a similar question before. This one is related, but different.
Right now: if you insert an image in a post as a thumbnail by the media-library, you can choose between 4 different sizes: thumbnail, medium, big and actual size. This is fine. However: the dimensions of the thumbnail are determined by whether the image is landscape or portrait. You can set a maximum width or height in your media-settings. Maximum 300 width and maximum 300 height, for instance, will make a landscape image 300px width and a portrait image 300px height. So it won't be always 300px wide. Only if it's a landscape image.
Please correct me, if I'm mistaken, but this is what I've encountered so far.
The point: my client used to work with movable type, but decided to switch to wp. In mt, however, you could set a maximum width of a thumbnail, so that a thumbnail would be always this width, regardless of it being portrait or landscape. He wanted to have all of his thumbnails the same width, regardless of its orientation.
This is not compatible with the way wp works, since the width will depend on the image's orientation.
Question: how to make wp work like my client wants (ie: to set all the thumbnails the same width, whether landscape or portrait)
And yes, the question is very similar to the one I referred to in the beginning, but that one was concerned with post-thumbnails which would be always the same size and this fixed width could be set within templates. In this case this is different: images are inserted in posts and the media-library determines the size.
Not sure if I made myself clear. If I have: anyone has a solution? Be it a plugin (haven't found one yet) or a hack. If I haven't: shoot me and I'll try to clarify.