Add clipboard paste feature to TweetDeck. Note that this script isn't compatible with Firefox or other Gecko-based browser.

tweetdeck-page-image(blink-only).user.js

/* tweetdeck-paste-image.js
 * License: WTFPL
 */
$(document.body).on('paste', function (event) {
    if ($('.js-add-image-button').hasClass('is-disabled')) {
        return;
    }
    var items = event.originalEvent.clipboardData.items;
    var item = items[0];
    if (item.kind !== 'file') return;
    var files = [ item.getAsFile() ];
    // 트윗 입력창을 닫은 이후에 멘션 안 남게
    if (!$('.app-content').hasClass('is-open')) {
        $(document).trigger('uiComposeTweet', { type: 'tweet' });
    }
    $(document).trigger('uiFilesAdded', { files });
});

see also: zn/tweetdeck-paste-image.user.js (compatible with Firefox)