Add separate section describing collapsed items.

manual/tracy.tex

@@ -874,6 +874,13 @@ The timeline view may be focused on the frames, by clicking or dragging the \LMB
 
 The timeline is the most important element of the profiler UI. All the captured data is displayed there, laid out on the horizontal axis, according to the flow of time. The view is split into three parts: the time scale, the frame sets and the combined zones, locks and plots display.
 
+\subparagraph{Collapsed items}
+\label{collapseditems}
+
+Due to extreme differences in time scales, you will almost constantly see events that are too small to be displayed on the screen. Such events have preset minimum size (so they can be seen) and are marked with a zig-zag pattern, to indicate that you need to zoom-in to see more detail.
+
+The zig-zag pattern can be seen applied to frame sets on figure~\ref{framesetsfig}, and to zones on figure~\ref{zoneslocks}.
+
 \paragraph{Time scale}
 
 The time scale is a quick aid in determining the relation between screen space and the time it represents (figure~\ref{timescale}).
@@ -940,7 +947,7 @@ Frames from each frame set are displayed directly underneath the time scale. Eac
 \label{framesetsfig}
 \end{figure}
 
-On figure~\ref{framesetsfig} we can see the fully described frames~312 and 347. The description consists of the frame name, which is \emph{Frame} for the default frame set (section~\ref{markingframes}) or the name you used for the secondary name set (section~\ref{secondaryframeset}), the frame number and the frame time. The frame~348 is too small to be fully displayed, so only the frame time is shown. The frame~349 is even smaller, with no space for any text. Moreover, frames~313~to~346 are too small to be displayed individually, so they are replaced with a zig-zag pattern.
+On figure~\ref{framesetsfig} we can see the fully described frames~312 and 347. The description consists of the frame name, which is \emph{Frame} for the default frame set (section~\ref{markingframes}) or the name you used for the secondary name set (section~\ref{secondaryframeset}), the frame number and the frame time. The frame~348 is too small to be fully displayed, so only the frame time is shown. The frame~349 is even smaller, with no space for any text. Moreover, frames~313~to~346 are too small to be displayed individually, so they are replaced with a zig-zag pattern, as described in section~\ref{collapseditems}.
 
 You can also see that there are frame separators, projected down to the rest of the timeline view. Note that only the separators for the currently selected frame set are displayed. You can make a frame set active by clicking the \LMB{}~left mouse button on a frame set row you want to select (also see section~\ref{controlmenu}).
 
@@ -994,7 +1001,7 @@ The left hand side \emph{index area} of the timeline view displays various label
 
 \subparagraph{Zones}
 
-In an example on figure~\ref{zoneslocks} you can see that there are two threads: \emph{Main thread} and \emph{Streaming thread}\footnote{By clicking on a thread name you can temporarily disable display of the zones in this thread.}. We can see that the \emph{Main thread} has two root level zones visible: \emph{Update} and \emph{Render}. The \emph{Update} zone is split into further sub-zones, some of which are too small to be displayed at the current zoom level. This is indicated by drawing a zig-zag pattern over the merged zones box, with the number of collapsed zones printed in place of zone name. We can also see that the \emph{Physics} zone acquires the \emph{Physics lock} mutex for the most of its run time.
+In an example on figure~\ref{zoneslocks} you can see that there are two threads: \emph{Main thread} and \emph{Streaming thread}\footnote{By clicking on a thread name you can temporarily disable display of the zones in this thread.}. We can see that the \emph{Main thread} has two root level zones visible: \emph{Update} and \emph{Render}. The \emph{Update} zone is split into further sub-zones, some of which are too small to be displayed at the current zoom level. This is indicated by drawing a zig-zag pattern over the merged zones box (section~\ref{collapseditems}), with the number of collapsed zones printed in place of zone name. We can also see that the \emph{Physics} zone acquires the \emph{Physics lock} mutex for the most of its run time.
 
 Meanwhile the \emph{Streaming thread} is performing some \emph{Streaming jobs}. The first \emph{Streaming job} sent a message (section~\ref{messagelog}), which in addition to being listed in the message log is being indicated by the triangle over the thread separator. When there are multiple messages in one place, the triangle outline changes to a filled triangle.