My Lumix DMC-G1 histogram shows square area

The histogram is a tool that is useful to the photographer that shows a graph that represents how much color or bright and dark areas are in a photo. If you're looking at a photo that has a larger portion of the histogram graph on the left, it means there's a lot of dark / black tones - and that details in those areas are likely lost. The same holds true if the graph was heavy to the right edge - but it would mean there is a lot of bright or whites. Subtle details in these areas would also be lost. You can use the graph to adjust your exposure so that these details are visible. A wedding dress that lacks the fine lace details because the whites were "blown" (over-exposed) lacks interest when compared to a photo that preserves the details. Here's a link to a site with some great info in general - and about histograms specifically. Check it out.

Tinker with exposure settings to move the large areas of the graph away from the edges - this will show the details. You can switch the histogram off and on as you see fit.

You probably changed dioptre adjustment in your camera. There should be a adjustment ring next to the eyepiece.

Yeah,why did you half press the shutter?When you take a photo,you should press the shutter with force quickly.I think you didn't set your Panasonic Lumix DMC-FZ5 Camera at a proper mode for the scene,shot with a correct the next time.Wish helpful to you.

I found 2 different Lumix TZ3 cameras.
http://www2.panasonic.com/webapp/wcs/stores/servlet/PNAEndecaSearchCmd?N=779832097+250033510&Ne=&Ns=&Nr=12001&No=0&Ntt=tz3&Ntk=SupportSearch&URL=vSupportSearch&cmTag=false&cm_sp=&cn=&catalogId=13401&storeId=15001

In the manual, I couldn't find a reference to a bluish color.

In FAQ's, I found the following:
What is “Intelligent Auto Mode” (or IA Mode)?
“IA mode” automatically activates MEGA O.I.S., Intelligent ISO Control, Face Detection, Intelligent Scene Selector, Intelligent Exposure, and Quick Auto Focus to match your subject and shooting situation. IA Mode is a great mode for beginning photographers
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http://www2.panasonic.com/webapp/wcs/stores/servlet/vSupportHowToGuideDetail?storeId=15001&idval=UCM_STG_CNT_032308&catname=Lumix+Digital+Cameras&title=How to Take Better Photos

switch your camera on the dial to the mountains. press the set button. scroll down to the wrench.scroll in the wrench menu down to the thrid page which has the histogram on it- turn it on. it isn't available in all modes. I'm sure there are other ways to do it- this is how I found it.

It sounds like it could be one of the settings showing the histogram - Check by taking picture in a different mode this should disappear.

I have, after sifting through the 144-page manual, figured out what the problem is! At some point you must have set the "Auto-Bracket" setting to on - I did the same thing! To turn this off, put it in any of the Scene or Manual Exposure modes, then press the up (↑) key until "Auto-Bracket" comes up. Then, using the left or right (←,→) keys, set it to Zero (0). This should hopefully solve your problem! :)

Flashig areas show HIGH KEY or HIGHLIGHTS in image, these areas indicate where exposure compensation can be made. They also change to normal function on first magnification point.

Check the manual on highlights also good reading in the histogram section and you will start to understand about contrast and exposure.
Have FUN.

GORDO

Multi-segment metering uses 256 segments to measure luminance and color. This data is combined with distance information to calculate the camera exposure. This advanced metering system will accurate worry-free exposures in almost all situations including backlight condition. Spot metering uses a small circle area within the middle of image to calculate the exposure. The spot allows precise exposure measurements of a particular object without being influenced by extremely bright or dark areas within the scene. Center weighted measures light values over the entire image area with emphasis given in the central region. In backlight condition or when the subject is not in the center of image, exposure compensation will be required.

A histogram is a graphic representation of the distribution of brightness values in an image. The C-5500 has two histograms. One displays a real-time graph on the LCD screen as you compose your images and during the Quick View of images after they are shot. The DIRECT histogram displays potentially over and under-exposed areas in the image with a grid of squares—red for over-exposure and blue for under-exposure. You can set the histogram to OFF to prevent the histogram from appearing.