WowAce

This is my personal preference, maybe you could use if you think it's an improvement.
let code speak, in BuyFrame.xml around line 824, under <EditBox name="BuyName"

					<OnEnterPressed>
						if self:GetText() ~= "" then
							AuctionLite:AuctionFrameBuy_Search();
<!--							self:ClearFocus();-->
							self:HighlightText()
						end
					</OnEnterPressed>

When the user presses Enter, the focus doesnt clear and the text is selected.
The point is to make successive searches easier, the user can use left/right arrows to modify the search string, or just type a new one while the old one is selected, and most importantly it works without Mouse interference. If user wants to de-focus she can still type Esc.