I'm not fully understand the first request. About the second, there are same request about this, but I think it was not quite simple to implement. The third one, can you see the keyboard shortcuts plugins? This show all the menu items and it's shortcut keys.

1. The example for this is visual C# studio and AVR studio 6
Example code :

long MyFunction(int param1, char param2); // declaration
long MyFunction(int param1, short param2, long param3);

long numbs = MyFunction( adder, addee);

When the cursor is positioned inside parentheses (from
'adder' until 'addee'), the popup shows the declaration plus
up/down arrow to select the overloads along with its
parameter. If the cursor placed before comma ',' it will
shows (example):

AV [1 of 2] MyFunction(param1, param2)
(function summary)
int param1 (param1 summary)
return long (return summary)

If the cursor placed after comma ',' it will shows (example):

AV [1 of 2] MyFunction(param1, param2)
(function summary)
char param2 (param2 summary)
return long (return summary)

If user add another comma and placed the cursor after second
comma :

AV [2 of 2] MyFunction(param1, param2, param3)
(function summary)
long param3 (param3 summary)
return long (return summary)

AV : the up and down arrows. Scintilla have this feature.
Current C:B doesn't use this feat, so all overloads shown at
once and cropped if the screen not tall enough.

The code completion also shows possible variables to put as
adder / addee just like current C:B build. But the params
pop-up still shown along with the CC. When user press CTRL,
both CC and params pop-up becomes transparent. This useful
if both pop-up becomes obstruction. On AVR studio (C IDE
based on VS), it not transparent, but hidden temporary.

2. Function, params, and return summaries is possible on C#
since it has good documentation system (using XML). The AVR
studio uses the comment above function declaration on header
file to shown. The visual C++ uses header view window below
the editor instead. Since C:B can extract symbol to put in
symbol browser, I think it can extract the comment above the
symbol. Maybe you can use SQLite to store project symbols
along with its comment. If you do use SQLIte, maybe you can
scan functions,constants, and variables from inherited class
and put it on symbol browser (C:B already implement this but
only used it for code completion)

Using doxygen documentation is not easy to implement I
think. It needs separate plugin to scan doxygen
documentation and match it with the source code. Or maybe
just scan for \brief, \params, \return

3. Yes, now I see inside editor menu. Thanks.

Thanks.

Dear asugix, first, thanks for writing so detailed information. I just carefully read it, but I'm sorry it is still not so clear. 1a, you first example shows that the cursor in parentheses will determine the showed parameter in the tip window. 1b, Scintilla have this feature, but I have not notices this feature, I will try to find it. Or can you give me a direction? 1c, Quote" The code completion also shows possible variables to put as adder / addee just like current C:B build. But the params pop-up still shown along with the CC. When user press CTRL, both CC and params pop-up becomes transparent. This useful if both pop-up becomes obstruction. On AVR studio (C IDE based on VS), it not transparent, but hidden temporary." I do not clear understand this, can you show some images or steps?

2a, I agree, the document(c++ comments) can be extracted we have a TokensTree to store symbols info(our own tree structure like sqlite), but comments can put before or after the symbol, how do you know which belongs to which?

This is the screenshoot : 
https://www.box.com/s/063ebec56458dd390a2e
(next time, please mention where to upload file)

1a and 1c. About cursor position, please look at the VCS
example, this is Visual C#. Look at the cursor position and
look at the note "this becomes transparent when I press CTRL". 

1b. Look at the
http://www.scintilla.org/ScintillaDoc.html#CallTips.
Please forgive me because I misunderstood this Calltips
explanation. It is some years ago I experimenting with
scintilla for my C# project.

So this is my idea:
1. have a variable to hold focus status (use enum), default
"editor"
2. When showing calltip or user click the calltip
(SCN_CALLTIPCLICK), set the status to "calltip". At this
status, intercept the UP and DOWN arrow. Show calltip with
text something like "\001 1 of 3 \002". And show the first
function overload. When user press DOWN, change the text
"\001 2 of 3 \002". And show the second function overload.
something like that.
3. When showing code completion or select its item, set the
status to "CC". Remove UP DOWN interception from calltip and
change to CC.

I don't know if calltip is always canceled upon CC showing
up, and vice versa.

2a. To make it easy, just take the comments before the symbol.

Visual C#, Visual C++, Visual Basic, CSS always put
documentation comments (sometimes a paragraph) before "the
declaration/definition" of the symbol, extract this one.
Otherwise, it just explanation of that line to remind the
programmer of the algorithm. Example :

-------------------------------------------------------------------------------------
---
//set current context (ignore because this not
declaration/definition)
SetCurrent(m_context);    

/// change size (ignore because one paragraph away from
clientSize)

/*!
holds size
(extract, this should be the documentation) */ 
int clientSize; /// declare size (ignore, this usually not
documentation)

/// ignore because this is not declaration
clientSize = 30;   

///extract because this contain declaration
int parentSize = 50;

///extract because this is declaration / definition
bool resize (int x, int y)
{
    clientX = x;
}

-------------------------------------------------------------------------------------
----

In doxygen-style comments, the key is '<' character after
doxygen comment start tokens:
1. documentation after symbol always started with: "/*!<",
"/**<", or "///<" example :

#define PORTC   0x88 ///< portc for atmega8 processor

2. documentation before symbol doesn't started by "<" example:

/*!
\brief resizing
\ param x size of X
\param y size of Y
\return success or not
*/
bool resize (int x, int y)
{
}

thankyou