I would like to change the style of the component Flex Edition . The functionality is what I need but I find too much space it occupies such module for which I would like to make changes to style sheets
The Editor is a skinnable component. https://developers.arcgis.com/flex/api-reference/index.html?com/esri/ags/components/Editor.html&com/esri/ags/components/class-list.html
The API download contains not only the SWC library but also the skins for Editor etc. Look for the Editor* files within the ArcGIS_Flex\src\com\esri\ags\skins folder of the zip.
https://developers.arcgis.com/flex/guide/styling-and-skinning-overview.htm has more info, including exmaples for skinning Navigation and ScaleBar components.