Constrain aspect ratio when Crop tool is selected

`A`

All hotkeys for Photoshop Lightroom 4 (Windows)

Working with Panels Show/hide side panels	`Tab`
Working with Panels Show/hide all panels	`Shift` + `Tab`
Working with Panels Show/hide toolbar	`T`
Working with Panels Show/hide Module Picker	`F5`
Working with Panels Show/hide Filmstrip	`F6`
Working with Panels Show/hide left panels	`F7`
Working with Panels Show/hide right panels	`F8`
Working with Panels Toggle solo mode	`Alt` +click a panel
Working with Panels Open a new panel without closing soloed panel	`Shift` +click a panel
Working with Panels Open/close all panels	`Ctrl` +click a panel
Working with Panels Open/close left panels, top to bottom	`Ctrl` + `Shift` + `0` … `5`
Working with Panels Open/close right panels, Library and Develop modules, top to bottom	`Ctrl` + `0` … `8`
Working with Panels Open/close right panels, Slideshow, Print, and Web modules, top to bottom	`Ctrl` + `0` … `7`
Navigating Modules Go to Library module	`Ctrl` + `Alt` + `1`
Navigating Modules Go to Develop module	`Ctrl` + `Alt` + `2`
Navigating Modules Go to Slideshow module	`Ctrl` + `Alt` + `3`
Navigating Modules Go to Print module	`Ctrl` + `Alt` + `4`
Navigating Modules Go to Web module	`Ctrl` + `Alt` + `5`
Navigating Modules Go back / go forward	`Ctrl` + `Alt` + `Arrow Left` / `Arrow Right`
Navigating Modules Go back to previous module	`Ctrl` + `Alt` + `Arrow Up`
Changing Views and Screen Modes Go to Library module	`Ctrl` + `Alt` + `1`
Changing Views and Screen Modes Go to Develop module	`Ctrl` + `Alt` + `2`
Changing Views and Screen Modes Go to Slideshow module	`Ctrl` + `Alt` + `3`
Changing Views and Screen Modes Go to Print module	`Ctrl` + `Alt` + `4`
Changing Views and Screen Modes Go to Web module	`Ctrl` + `Alt` + `5`
Changing Views and Screen Modes Go back / go forward	`Ctrl` + `Alt` + `Arrow Left` / `Arrow Right`
Changing Views and Screen Modes Go back to previous module	`Ctrl` + `Alt` + `Arrow Up`
Using Secondary Window Open secondary window	`F11`
Using Secondary Window Enter Grid view	`Shift` + `G`
Using Secondary Window Enter normal Loupe view	`Shift` + `E`
Using Secondary Window Enter locked Loupe view	`Ctrl` + `Shift` + `Enter`
Using Secondary Window Enter Compare view	`Shift` + `C`
Using Secondary Window Enter Survey view	`Shift` + `N`
Using Secondary Window Enter Slideshow view	`Ctrl` + `Alt` + `Shift` + `Enter`
Using Secondary Window Enter full-screen mode (requires a second monitor)	`Shift` + `F11`
Using Secondary Window Show/hide Filter bar	`Shift` + `\`
Using Secondary Window Zoom in / zoom out	`Ctrl` + `Shift` + `=` / `-`
Managing photos and catalog Import photos from disk	`Ctrl` + `Shift` + `I`
Managing photos and catalog Open catalog	`Ctrl` + `O`
Managing photos and catalog Open Preferences	`Ctrl` + `,` (comma)
Managing photos and catalog Open Catalog Settings	`Ctrl` + `Alt` + `,` (comma)
Managing photos and catalog Create new subfolder (segmented tethered capture)	`Ctrl` + `Shift` + `T`
Managing photos and catalog Hide/show tether capture bar	`Ctrl` + `T`
Managing photos and catalog Create a new folder in the Library module	`Ctrl` + `Shift` + `N`
Managing photos and catalog Create virtual copy (Library and Develop module only)	`Ctrl` + `‘` (apostrophe)
Managing photos and catalog Show in Explorer / Finder (Library and Develop module only)	`Ctrl` + `R`
Managing photos and catalog Go to next/previous photo in the Filmstrip	`Arrow Right` / `Arrow Left`
Managing photos and catalog Select multiple folders or collections (in Library, Slideshow, Print, and Web modules)	`Shift` +click / `Ctrl` +click
Managing photos and catalog Rename photo (in Library module)	`F2`
Managing photos and catalog Delete selected photo(s)	`Backspace` / `Delete`
Managing photos and catalog Remove selected photo(s) from catalog	`Alt` + `Backspace`
Managing photos and catalog Delete selected photo(s) and move to Recycling Bin	`Ctrl` + `Alt` + `Shift` + `Backspace`
Managing photos and catalog Delete rejected photo(s)	`Ctrl` + `Backspace`
Managing photos and catalog Edit in Photoshop	`Ctrl` + `E`
Managing photos and catalog Open in other editor	`Ctrl` + `Alt` + `E`
Managing photos and catalog Export selected photo(s)	`Ctrl` + `Shift` + `E`
Managing photos and catalog Export with previous settings	`Ctrl` + `Alt` + `Shift` + `E`
Managing photos and catalog Open plug-in manager	`Ctrl` + `Alt` + `Shift` + `,` (comma)
Managing photos and catalog Print selected photo	`Ctrl` + `P`
Managing photos and catalog Open Page Setup dialog box	`Ctrl` + `Shift` + `P`
Comparing photos in the Library module Switch to Loupe view	`E` / `Enter`
Comparing photos in the Library module Switch to Grid view	`G` / `Esc`
Comparing photos in the Library module Switch to Compare view	`C`
Comparing photos in the Library module Switch to Survey view	`N`
Comparing photos in the Library module Switch from Grid to Loupe view	`Space` / `E`
Comparing photos in the Library module Swap select and candidate photos in Compare view	`Arrow Down`
Comparing photos in the Library module Make next photos select and candidate in Compare view	`Arrow Up`
Comparing photos in the Library module Toggle Zoom view	`Z`
Comparing photos in the Library module Zoom in / zoom out in Loupe view	`Ctrl` + `=` / `-`
Comparing photos in the Library module Scroll up/down zoomed photo in Loupe view (also works in Develop and Web modules)	`Page Up` / Page Down on full-size keyboard
Comparing photos in the Library module Go to beginning/end of Grid view	`Home` / `End`
Comparing photos in the Library module Play impromptu slide show	`Ctrl` + `Enter`
Comparing photos in the Library module Rotate photo right / left (clockwise/counterclockwise)	`Ctrl` + `]` / `[`
Comparing photos in the Library module Increase/decrease Grid thumbnail size	`=` /-
Comparing photos in the Library module Scroll up/down Grid thumbnails	`Page Up` / Page Down on full-size keyboard
Comparing photos in the Library module Toggle cell extras	`Ctrl` + `Shift` + `H`
Comparing photos in the Library module Show/hide badges	`Ctrl` + `Alt` + `Shift` + `H`
Comparing photos in the Library module Cycle Grid views	`J`
Comparing photos in the Library module Open Library view options	`Ctrl` + `J`
Comparing photos in the Library module Select multiple discrete photos	`Ctrl` +click
Comparing photos in the Library module Select multiple contiguous photos	`Shift` +click
Comparing photos in the Library module Select all photos	`Ctrl` + `A`
Comparing photos in the Library module Deselect all photos	`Ctrl` + `D`
Comparing photos in the Library module Select only active photo	`Ctrl` + `Shift` + `D`
Comparing photos in the Library module Deselect active photo	`/`
Comparing photos in the Library module Add previous/next photo to selection	`Shift` + `Arrow Left` / `Arrow Right`
Comparing photos in the Library module Select all flagged photos	`Ctrl` + `Alt` + `A`
Comparing photos in the Library module Deselect unflagged photos	`Ctrl` + `Alt` + `Shift` + `D`
Comparing photos in the Library module Group into stack	`Ctrl` + `G`
Comparing photos in the Library module Unstack	`Ctrl` + `Shift` + `G`
Comparing photos in the Library module Toggle stack	`S`
Comparing photos in the Library module Move to top of stack	`Shift` + `S`
Comparing photos in the Library module Move up in stack / move down in stack	`Shift` + `[` / `]`
Rating and Filtering Photos Set star rating	`1` … `5`
Rating and Filtering Photos Set star rating and go to next photo	`Shift` + `1` … `5`
Rating and Filtering Photos Remove star rating	`0` (zero)
Rating and Filtering Photos Remove star rating and go to next photo	`Shift` + `0` (zero)
Rating and Filtering Photos Increase / decrease rating by 1 star	`]` / `[`
Rating and Filtering Photos Assign a red label	`6`
Rating and Filtering Photos Assign a yellow label	`7`
Rating and Filtering Photos Assign a green label	`8`
Rating and Filtering Photos Assign a blue label	`9`
Rating and Filtering Photos Assign a color label and go to next photo	`Shift` + `6` … `9`
Rating and Filtering Photos Flag photo as a pick	`P`
Rating and Filtering Photos Flag photo as a pick and go to next photo	`Shift` + `P`
Rating and Filtering Photos Flag photo as a reject	`X`
Rating and Filtering Photos Flag photo as a reject and go to next photo	`Shift` + `X`
Rating and Filtering Photos Unflag photo	`U`
Rating and Filtering Photos Unflag photo and go to next photo	`Shift` + `U`
Rating and Filtering Photos Increase / decrease flag status	`Ctrl` + `Arrow Up` / `Arrow Down`
Rating and Filtering Photos Cycle flag settings	`‘`
Rating and Filtering Photos Refine photos	`Ctrl` + `Alt` + `R`
Rating and Filtering Photos Show/hide Library Filter bar	`\`
Rating and Filtering Photos Open multiple filters in the Filter bar	`Shift` +click filter labels
Rating and Filtering Photos Toggle filters on/off	`Ctrl` + `L`
Rating and Filtering Photos Find photo in the Library module	`Ctrl` + `F`
Collections Create a new collection in the Library module	`Ctrl` + `N`
Collections Add to Quick Collection	`B`
Collections Add to Quick Collection and go to next photo	`Shift` + `B`
Collections Show Quick Collection	`Ctrl` + `B`
Collections Save Quick Collection	`Ctrl` + `Alt` + `B`
Collections Clear Quick Collection	`Ctrl` + `Shift` + `B`
Collections Set as target collection	`Ctrl` + `Alt` + `Shift` + `B`
Metadata and Keywords in the Library module Add keywords	`Ctrl` + `K`
Metadata and Keywords in the Library module Edit keywords	`Ctrl` + `Shift` + `K`
Metadata and Keywords in the Library module Set a keyword shortcut	`Ctrl` + `Alt` + `Shift` + `K`
Metadata and Keywords in the Library module Add/remove keyword shortcut from selected photo	`Shift` + `K`
Metadata and Keywords in the Library module Enable painting	`Ctrl` + `Alt` + `K`
Metadata and Keywords in the Library module Add a keyword from a keyword set to selected photo	`Alt` + 1-9
Metadata and Keywords in the Library module Cycle forward / backward through keyword sets	`Alt` + `0` (zero)/ `Alt` + `Shift` + `0` (zero)
Metadata and Keywords in the Library module Copy/paste metadata	`Ctrl` + `Alt` + `Shift` + `C` / `Ctrl` + `Alt` + `Shift` + `V`
Metadata and Keywords in the Library module Save metadata to file	`Ctrl` + `S`
Develop Module Convert to grayscale	`V`
Develop Module Auto tone	`Ctrl` + `U`
Develop Module Auto white balance	`Ctrl` + `Shift` + `U`
Develop Module Edit in Photoshop	`Ctrl` + `E`
Develop Module Copy/paste Develop settings	`Ctrl` + `Shift` + `C` / `Ctrl` + `Shift` + `V`
Develop Module Paste settings from previous photo	`Ctrl` + `Alt` + `V`
Develop Module Copy After settings to Before	`Ctrl` + `Alt` + `Shift` + `Arrow Left`
Develop Module Copy Before settings to After	`Ctrl` + `Alt` + `Shift` + `Arrow Right`
Develop Module Swap Before and After settings	`Ctrl` + `Alt` + `Shift` + `Arrow Up`
Develop Module Increase/decrease selected slider in small increments (or +/-)	`Arrow Up` / `Arrow Down`
Develop Module Increase/decrease selected slider in larger increments (or Shift++/-)	`Shift` + `Arrow Up` / `Arrow Down`
Develop Module Cycle through Basic panel settings (forward/backward)	`.` / `,`
Develop Module Reset a slider	Double-click slider name
Develop Module Reset a group of sliders	`Alt` +click group name
Develop Module Reset all settings	`Ctrl` + `Shift` + `R`
Develop Module Sync settings	`Ctrl` + `Shift` + `S`
Develop Module Sync settings bypassing Synchronize Settings dialog box	`Ctrl` + `Alt` + `S`
Develop Module Toggle Auto Sync	`Ctrl` +click Sync button
Develop Module Enable Auto Sync	`Ctrl` + `Alt` + `Shift` + `A`
Develop Module Match total exposures	`Ctrl` + `Alt` + `Shift` + `M`
Develop Module Select White Balance tool (from any module)	`W`
Develop Module Select the Crop tool (from any module)	`R`
Develop Module Constrain aspect ratio when Crop tool is selected	`A`
Develop Module Crop to same aspect ratio as previous crop	`Shift` + `A`
Develop Module Crop from center of photo	`Alt` +drag
Develop Module Cycle Crop grid overlay	`O`
Develop Module Cycle Crop grid overlay orientation	`Shift` + `O`
Develop Module Switch crop between portrait and landscape orientation	`X`
Develop Module Reset crop	`Ctrl` + `Alt` + `R`
Develop Module Select the Spot Removal tool	`Q`
Develop Module Select the Adjustment Brush tool (from any module)	`K`
Develop Module Select the Graduated Filter tool	`M`
Develop Module Increase/decrease brush size	`]` / `[`
Develop Module Increase/decrease brush feathering	`Shift` + `]` / `[`
Develop Module Switch between local adjustment brush A and B	`/`
Develop Module Temporarily switch from brush A or B to Eraser	`Alt` +drag
Develop Module Paint a horizontal or vertical line	`Shift` +drag
Develop Module Increase/decrease Amount	Drag adjustment pin right/left
Develop Module Show/hide local adjustment pin	`H`
Develop Module Show/hide local adjustment mask overlay	`O`
Develop Module Cycle local adjustment mask overlay colors	`Shift` + `O`
Develop Module Select Targeted Adjustment tool to apply a Tone Curve adjustment	`Ctrl` + `Alt` + `Shift` + `T`
Develop Module Select Targeted Adjustment tool to apply a Hue adjustment	`Ctrl` + `Alt` + `Shift` + `H`
Develop Module Select Targeted Adjustment tool to apply a Saturation adjustment	`Ctrl` + `Alt` + `Shift` + `S`
Develop Module Select Targeted Adjustment tool to apply a Luminance adjustment	`Ctrl` + `Alt` + `Shift` + `L`
Develop Module Select Targeted Adjustment tool to apply a Grayscale Mix adjustment	`Ctrl` + `Alt` + `Shift` + `G`
Develop Module Deselect Targeted Adjustment tool	`Ctrl` + `Alt` + `Shift` + `N`
Develop Module Show clipping	`J`
Develop Module Rotate photo right / left (clockwise/counterclockwise)	`Ctrl` + `]` / `[`
Develop Module Toggle between Loupe and 1:1 Zoom preview	`Space` / `Z`
Develop Module Zoom in / zoom out	`Ctrl` + `=` / `-`
Develop Module Play impromptu slide show	`Ctrl` + `Enter`
Develop Module View Before and After left/right	`Y`
Develop Module View Before and After top/bottom	`Alt` + `Y`
Develop Module View Before and After in a split screen	`Shift` + `Y`
Develop Module View Before only	`\`
Develop Module Create a new snapshot	`Ctrl` + `N`
Develop Module Create a new preset	`Ctrl` + `Shift` + `N`
Develop Module Create a new preset folder	`Ctrl` + `Alt` + `N`
Develop Module Open Develop view options	`Ctrl` + `J`
Slideshow module Play slide show	`Enter`
Slideshow module Play impromptu slide show	`Ctrl` + `Enter`
Slideshow module Pause slide show	`Space`
Slideshow module Preview slide show	`Alt` + `Enter`
Slideshow module End slide show	`Esc`
Slideshow module Go to next slide / Go to previous slide	`Arrow Right` / `Arrow Left`
Slideshow module Rotate photo right / left (clockwise/counterclockwise)	`Ctrl` + `]` / `[`
Slideshow module Show/hide guides	`Ctrl` + `Shift` + `H`
Slideshow module Export PDF slide show	`Ctrl` + `J`
Slideshow module Export JPEG slide show	`Ctrl` + `Shift` + `J`
Slideshow module Export video slide show	`Ctrl` + `Alt` + `J`
Slideshow module Create a new slide show template	`Ctrl` + `N`
Slideshow module Create a new slide show template folder	`Ctrl` + `Shift` + `N`
Slideshow module Save slide show settings	`Ctrl` + `S`
Print module Print	`Ctrl` + `P`
Print module Print one copy	`Ctrl` + `Alt` + `P`
Print module Open Page Setup dialog box	`Ctrl` + `Shift` + `P`
Print module Open Print Settings dialog box	`Ctrl` + `Alt` + `Shift` + `P`
Print module Go to first page / go to last page	`Ctrl` + `Shift` + `Arrow Left` / `Arrow Right`
Print module Go to previous page / go to next page	`Ctrl` + `Arrow Left` / `Arrow Right`
Print module Show/hide guides	`Ctrl` + `Shift` + `H`
Print module Show/hide rulers	`Ctrl` + `R`
Print module Show/hide page bleed	`Ctrl` + `Shift` + `J`
Print module Show/hide margins and gutters	`Ctrl` + `Shift` + `M`
Print module Show/hide image cells	`Ctrl` + `Shift` + `K`
Print module Show/hide dimensions	`Ctrl` + `Shift` + `U`
Print module Play impromptu slide show	`Ctrl` + `Enter`
Print module Rotate photo right / left (clockwise/counterclockwise)	`Ctrl` + `]` / `[`
Print module Create a new print template	`Ctrl` + `N`
Print module Create a new print template folder	`Ctrl` + `Shift` + `N`
Print module Save print settings	`Ctrl` + `S`
Web module Reload web gallery	`Ctrl` + `R`
Web module Preview in browser	`Ctrl` + `Alt` + `P`
Web module Play impromptu slide show	`Ctrl` + `Enter`
Web module Export web gallery	`Ctrl` + `J`
Web module Create a new web gallery template	`Ctrl` + `N`
Web module Create a new web gallery template folder	`Ctrl` + `Shift` + `N`
Web module Save web gallery settings	`Ctrl` + `S`
Using Help Display current module shortcuts	`Ctrl` + `/`
Using Help Go to current module Help	`Ctrl` + `Alt` + `/`
Using Help Open Community Help	`F1`