FlexCelGrid doesn't have tabs, actually we made it that way so you can use a tab control that has the same look and feel as the rest of your form. The border is a single line, which you can turn off just by setting borderstyle = bsnone.
In our demo (XlsViewer demo) the FlexCelGrid is inside a Delphi's TPageControl which is the one drawing the tabs and the borders. If instead of a standard TPageControl you use a different tab control, you will be able to completely change how tabs and borders around the grid look.
FlexCelGrid only draws the inside part of the grid, and in that part there isn't too much choice, it is just a boring spreadsheet, and we must look the most similar to Excel as we can. I just launched a FlexCelGrid app and opened the same file in Excel 2010, and they don't look that different (both in win7).
Excel 2010 has a little darker gray in the row and column headings (we use btnFace which in my machine is $0F0F0F and Excel 2010 uses $E8E3DF) If you want to change that you can by changing FlexCelGrid.FixedColor to be $E8E3DF.
Of course this is with the default "silver" theme in Excel 2010, if you change it to other theme colors will change.
The highlight in the cell is also different, FlexCel uses blue (it was the default in Excel at the time we made FlexCelGrid), but now Excel 2010 uses orange. Sadly this one isn't in a property you can change (it should be) But I don't think the blue looks bad anyway.
If as I think your issues are more with Delphi's TPageControl than with FlexCelGrid, then look at using other Tab control. If the issues are really with FlexCelGrid (that is, how the cells themselves are rendered) please send me some screenshots of how it looks and how Excel shows them so we can see if something can be done.
Thanks for your answer, I did see the Tabcontrol behind the grid in the demo after I posted my original message!
Unfortunately TMS Smoothcontrols only has a Tabpager and I could not get this to work (with my limited knowledge) with the FlexCelGrid as it creates multiple tabbed pages rather than one page with multiple tabs!
On another question Is it possible in the FlexCelGrid to change column colors from code?
When a template worksheet is loaded I wanted to highlight an entire column of interest.