The Panasonic GH2 (set to pal) has had two 1080 recording modes: 24p and 50i. I have never used the 50i mode but filmed in 24p which kdenlive was able to handle natively.
Some time ago Panasonic released a firmware update that enabled a 25p mode and this is the mostly preferred framerate, so I do always use it.

Now the problem is, that the 25p Progressive material comes in a 50i wrapper, and kdenlive is unable to handle the files. Pulling the files into either a 25p or 50p timeline shows that kdenlive can not play back the clips at all. Only heavy stuttering and short interface freezes on starting/stopping. Forcing the clips framerate to 25 in the clip properties makes the video play smoothly, but there is no scrubbing possible and starting playback on any timeline position makes the clip play from its beginning. Having two or more overlapping clips in timeline leads to image freezing and strange jumping while playback.

I am not really sure if that is an ffmpeg related issue because Blender play the clips smoothly when the project framerate is set to 50. (Although audio is too short) So I do not even know where to post a bug report ;)
VDPAU is enabled on my system, Kdenlive build with build script. So FFMPEG, MLT and KDENLIVE are most recent versions.

Has someone made the same experience or has some tips?

Here is a short panning clip if you want to try:

http://www.mediafire.com/file/byx1led9dxiteng/00000.MTS

Thank you ;)

Have you tried a quick remux into a mkv as progressive?

Yes, I have tried it but nothing changed in Kdenlive...
Blender (Which works with FFMPEG, too) can handle the files without problems, though you have to set the project's framerate up to 50.

But actually blender isn't handling them properly and does have a problem? As you're audio is short. I assume the reason is that blender is set to 25fps in the render panel and incorrectly interpreting the files as interlaced at 50i because of the container flaging it but putting them on the timeline as 25P, so doubling the length, as audio is being showed short (correct length) illustrates that it's a 25P source, blender is confused. :-)

Yes, i know what blender does or tries to do ;-)
With Blenders proper handling I meant that it does handle the files an I can scrub the timeline without problems. That Blender is limited here by the fact that it plays the input files with the projects framerate and does not resample the videos is a Blender internal thing we should not bothe.

PS: Blender is never confused, Blender simply never thinks ;)
The video is simply taken with as many frames as Blender gets from the encoder and then every frame in the video becomes one frame in the timeline. Regardless of the framerate specified by the file.
Audio is taken like a seperate import of an audio track and internally blender does not bother if it comes in one container with the video or not and if the durations match.

Well you have all the answers why Blender can scrub the timeline. Guess it's a bug report for MLT then. 25P HDV in a 50i container has same problems.