This was me with my 4.5year DD up until recently (I think I wrote a thread a while back about Fussy Eaters).
She had an incredibly limited diet - Smily Faces, M&S chicken pieces, fruit, cereals, yoghurts, bread. I tried everything, not making a fuss/praising when she did eat etc etc. Advice I received from Paediatrician/GP/HV all said the same - feed her what she will eat but adding different stuff every now and then.
She was "fussy" as a baby, never fussed for milk, weaning was awful and it went downhill from then. As I said, this was up until recently - when one day she asked for some pasta that we were having. Wolfed it down!
She nows eats pasta, spaghetti bol, roast potatoes, chicken (and Chicken Kiev!), corn on the cobs, sausages, cheese, pizza. She gulps down fruit but she's always like fruit since a baby. Tried mashed potato last night but didn't like (down to texture I think - she's very fussy with textures/smells).
I weaned/fed her exactly the same as my other 2 but they've always been excellent eaters.
Fussy eaters are extremely hard work and at times very frustrating. I don't think people appreciate how hard it is unless you've had a fussy eater - when I had my first 2 I was very smug about them and thought "no child of mine will be fussy" Lo and behold, I got one with No 3