How to create a 'headline' theme in beamer which occupies only a portion of the sidebar?

Question

The headline in beamer which spans the width of the top or height of the side in most examples I have seen displays the section/subsection/subsubsection labels. Can I produce a header/headline which is a specified portion/percentage of the slide size or length depending if it was placed along a particular edge?

I have in mind placing the headline as a stunted/shortened rectangle along the top, and beside it to have another 'rectangle' to display the frame title with a logo.

 \setbeamertemplate{frametitle}
{\vskip 0.25pt
  \leavevmode
  \hbox{%
    \begin{beamercolorbox}[wd=\paperwidth,ht=1.8ex,dp=1ex]{frametitle}%
     \insertsection\insertsubsection\\
    \raggedright\hspace*{5em}\Large\insertframetitle 
  \end{beamercolorbox}
  }%
  \vspace{-25pt}
  \hfill
  \includegraphics[width=1cm]{UCFLOGO}
  \hspace*{0.0cm}
  \vskip0pt
  %{\color{ucfBlack}\rule{\textwidth}{0.4mm}}
}


%footer
\setbeamertemplate{footline}
{
  \leavevmode%
  \hbox{%
  \begin{beamercolorbox}[wd=.4\paperwidth,ht=2.25ex,dp=1ex,center]{author in head/foot}%
  \usebeamerfont{author in head/foot}\insertshortauthor
  \end{beamercolorbox}%
  \begin{beamercolorbox}[wd=.6\paperwidth,ht=2.25ex,dp=1ex,center]{title in head/foot}%
    \usebeamerfont{title in head/foot}\insertshorttitle\hspace*{3em}
    \insertframenumber{} / \inserttotalframenumber\hspace*{1ex}
  \end{beamercolorbox}}%
  \vskip0pt%
}

Answer 1

Depends on the theme, but in most standard themes this should be possible.

As you did not provide any code for your headline, I am going to use the headline from the miniframe outer theme in the following:

\defbeamertemplate*{headline}{miniframes theme}
{%
  \begin{beamercolorbox}[colsep=1.5pt]{upper separation line head}
  \end{beamercolorbox}
  \begin{beamercolorbox}{section in head/foot}
    \vskip2pt\insertnavigation{\paperwidth}\vskip2pt
  \end{beamercolorbox}%
  \ifbeamer@theme@subsection%
    \begin{beamercolorbox}[colsep=1.5pt]{middle separation line head}
    \end{beamercolorbox}
    \begin{beamercolorbox}[ht=2.5ex,dp=1.125ex,%
      leftskip=.3cm,rightskip=.3cm plus1fil]{subsection in head/foot}
      \usebeamerfont{subsection in head/foot}\insertsubsectionhead
    \end{beamercolorbox}%
  \fi%
  \begin{beamercolorbox}[colsep=1.5pt]{lower separation line head}
  \end{beamercolorbox}
}

To adjust the width, you have to do two things

1. Specify the width of the beamercolorboxes width wd={⟨width⟩}
2. adjusting the width of the navigation element by modifying \insertnavigation{\paperwidth}

So for a headline spanning half the page:

\documentclass{beamer}
\usecolortheme{whale}

\setbeamertemplate{headline}{%
  \begin{beamercolorbox}[colsep=1.5pt, wd=.5\paperwidth]{upper separation line head}
  \end{beamercolorbox}
  \begin{beamercolorbox}[wd=.5\paperwidth]{section in head/foot}
    \vskip2pt\insertnavigation{.5\paperwidth}\vskip2pt
  \end{beamercolorbox}%
  \begin{beamercolorbox}[colsep=1.5pt, wd=.5\paperwidth]{lower separation line head}
  \end{beamercolorbox}
}

\begin{document}
    
\section{1}\begin{frame}\end{frame}
\section{2}\begin{frame}\end{frame}
\section{3}\begin{frame}\end{frame}
\section{4}\begin{frame}\end{frame}
\section{5}\begin{frame}\end{frame}
\section{6}\begin{frame}\end{frame}
\section{7}\begin{frame}\end{frame}
\section{8}\begin{frame}\end{frame}
\section{9}\begin{frame}\end{frame}
\section{10}\begin{frame}\end{frame}

\end{document}

(The colour theme is only loaded to make things more visible)